[BUG] MathExpressionConverter doesn't support negative numbers when in Arabic (ar_AR)

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Did you read the "Reporting a bug" section on Contributing file?

- [x] I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

### Current Behavior

When your `CultureInfo.CurrentCulture = new CultureInfo("ar-AR")` the MathExpressionConverter will raise an exception when the expression contains negative numbers (e.g. `x0 ? -90 : 90`):

> HResult: -2146233033 (0x80131537)
> Message: The input string '-90' was not in a correct format.

Here's the call stack:

at System.Number.ThrowFormatException[TChar](ReadOnlySpan`1 value)
at System.Double.Parse(String s)
at CommunityToolkit.Maui.Converters.MathExpression.ParsePrimary() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 365
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParsePower() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 333
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParseProduct() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 331
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParseSum() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 329
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParseCompare() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 327
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 357
at CommunityToolkit.Maui.Converters.MathExpression.ParseEquality() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 325
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParseLogicalAnd() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 323
at CommunityToolkit.Maui.Converters.MathExpression.ParseBinaryOperators(Regex BinaryOperators, Func`1 ParseNext) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 337
at CommunityToolkit.Maui.Converters.MathExpression.ParseLogicalOR() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 321
at CommunityToolkit.Maui.Converters.MathExpression.ParseConditional() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 302
at CommunityToolkit.Maui.Converters.MathExpression.ParseExpr() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 287
at CommunityToolkit.Maui.Converters.MathExpression.ParseExpression() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 282
at CommunityToolkit.Maui.Converters.MathExpression.CalculateResult() in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs:line 128
at CommunityToolkit.Maui.Converters.MathExpressionConverter.ConvertFrom(Object inputValue, String parameter, CultureInfo culture) in /_/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpressionConverter.shared.cs:line 25
at CommunityToolkit.Maui.Converters.BaseConverter`3.CommunityToolkit.Maui.Converters.ICommunityToolkitValueConverter.Convert(Object value, Type targetType, Object parameter, CultureInfo culture) in /_/src/CommunityToolkit.Maui/Converters/BaseConverter.shared.cs:line 91
at CommunityToolkit.Maui.Converters.ICommunityToolkitValueConverter.Microsoft.Maui.Controls.IValueConverter.Convert(Object value, Type targetType, Object parameter, CultureInfo culture) in /_/src/CommunityToolkit.Maui/Converters/ICommunityToolkitValueConverter.shared.cs:line 57
at Microsoft.Maui.Controls.Binding.GetSourceValue(Object value, Type targetPropertyType)
at Microsoft.Maui.Controls.BindingExpression.ApplyCore(Object sourceObject, BindableObject target, BindableProperty property, Boolean fromTarget, SetterSpecificity specificity)
at Microsoft.Maui.Controls.BindingExpression.Apply(Boolean fromTarget)
at Microsoft.Maui.Controls.BindingExpression.BindingExpressionPart.b__50_0()
at Microsoft.Maui.Controls.DispatcherExtensions.DispatchIfRequired(IDispatcher dispatcher, Action action)
at Microsoft.Maui.Controls.BindingExpression.BindingExpressionPart.PropertyChanged(Object sender, PropertyChangedEventArgs args)
at Microsoft.Maui.Controls.BindingExpression.WeakPropertyChangedProxy.OnPropertyChanged(Object sender, PropertyChangedEventArgs e)
at Microsoft.Maui.Controls.BindableObject.OnPropertyChanged(String propertyName)
at Microsoft.Maui.Controls.Element.OnPropertyChanged(String propertyName)
at Microsoft.Maui.Controls.BindableObject.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean didChange, Boolean willFirePropertyChanged)
at Microsoft.Maui.Controls.Element.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean changed, Boolean willFirePropertyChanged)
at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, Boolean silent)
at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value, SetterSpecificity specificity)
at Microsoft.Maui.Controls.CheckBox.Microsoft.Maui.ICheckBox.set_IsChecked(Boolean value)
at Microsoft.Maui.Handlers.CheckBoxHandler.OnChecked(Object sender, RoutedEventArgs e)
at WinRT._EventSource_global__Microsoft_UI_Xaml_RoutedEventHandler.EventState.b__1_0(Object sender, RoutedEventArgs e)
at ABI.Microsoft.UI.Xaml.RoutedEventHandler.Do_Abi_Invoke(IntPtr thisPtr, IntPtr sender, IntPtr e)

### Expected Behavior

The MathExpressionConverter should be able to handle expressions with negative numbers without encountering exceptions.

### Steps To Reproduce

The following is a XAML minimal repro case

```xaml

```

### Link to public reproduction project repository

https://github.com/stephenquan/MauiMCTMinusBug

### Environment

```markdown
- .NET MAUI CommunityToolkit: 12.0
- OS: Windows 11
- .NET MAUI: 9.0.70
```

### Anything else?

I believe the bug is on the following offending line: https://github.com/CommunityToolkit/Maui/blob/ecc51ed31434b09c6e32003149d10c13023af6f2/src/CommunityToolkit.Maui/Converters/MathExpressionConverter/MathExpression.shared.cs#L365