[Samples] `ToolkitSampleMultiChoiceOption` should take a converter method parameter/Action

## Problem Statement

@Arlodotexe I was just creating a sample for Expander and was using `ToolkitSampleMultiChoiceOption` for the expand direction of 'Down' or 'Up':

https://github.com/CommunityToolkit/Labs-Windows/blob/3b9d3c6d342bd27005410c751bf937dfc299b4e5/labs/Expander/samples/Expander.Sample/ExpanderFirstSamplePage.xaml.cs#L31

However, these are strings... so I needed to add a long unwieldy converter that most folks wouldn't need to the sample:

https://github.com/CommunityToolkit/Labs-Windows/blob/3b9d3c6d342bd27005410c751bf937dfc299b4e5/labs/Expander/samples/Expander.Sample/ExpanderFirstSamplePage.xaml#L11

https://github.com/CommunityToolkit/Labs-Windows/blob/3b9d3c6d342bd27005410c751bf937dfc299b4e5/labs/Expander/samples/Expander.Sample/ExpanderFirstSamplePage.xaml.cs#L40-L45

## Suggested Solution

It'd be nice if instead, we could have this be part of the Labs sample source generation process here to simplify they desired output for these scenarios:

```xml
ExpandDirection="{x:Bind ExpandDirection, Mode=OneWay}"
```

As in an app scenario, the developer is probably just using the enum type directly, this is a sample implementation detail in the current setup.

Ideally, we could specify the method/action for converting in the attribute (as an `Action` I guess or delegate, that should mean llambda or method are supported I think):

```cs
[ToolkitSampleMultiChoiceOption("ExpandDirection", title: "Expand Direction", converter:nameof(ConvertStringToDirection), "Down", "Up")]
...

public static MUXC.ExpandDirection ConvertStringToDirection(string direction) => direction switch
{
"Down" => MUXC.ExpandDirection.Down,
"Up" => MUXC.ExpandDirection.Up,
_ => throw new System.NotImplementedException(),
};
```

(I'm not sure how the current implementation works, so this may require two properties linked together, one bound to the generated UI that uses the string/radio connection, and another one which listens to that, passes through the function, and is the one bound by the sample.)

But the idea is, this would generate the `ExpandDirection` with the return type of the converter function instead of `string` and then when the user selects the option and updates the value would pass it through the action specified first.

Also, if a method is tagged in the attribute this way, we should hide it in the C# code view for displaying the sample code.

## Other Considerations

Or maybe we want it to be based off a `bool` for the sample:

```xml
ExpandDirection="{x:Bind local:ExpanderFirstSamplePage.ConvertBoolToDirection(IsExpanderDown), Mode=OneWay}"
``````

In this case the sample class would actually have two converters, one that converts our string to the bool being expected by the sample for `IsExpanderDown`, and then the one the sample is actually using to demonstrate mapping that to an enum.

```cs
[ToolkitSampleMultiChoiceOption("ExpandDirection", title: "Expand Direction", converter:nameof(ConvertStringToBool), "Down", "Up")]
...

// hidden from C# view
public static bool ConvertStringToBool(string direction) => direction switch
{
"Down" => true
"Up" => false,
_ => throw new System.NotImplementedException(),
};

// Still seen, as in use by example
public static MUXC.ExpandDirection ConvertBoolToDirection(bool direction) => direction switch
{
true => MUXC.ExpandDirection.Down,
false => MUXC.ExpandDirection.Up,
_ => throw new System.NotImplementedException(),
};
```

## Other Notes

The Sample Author may want to just show a converter, and that should be fine. This is more for cases with enums or other complex types where you want a simple selection choice and a simple binding (as would appear in an app).