ToolkitSampleButtonAction Attribute

### Describe the bug

Many samples need the option to perform an action or demonstrate a triggered event (like a notification for instance).

For instance, the current notification behavior needs to have button as part of its sample code:

https://github.com/CommunityToolkit/Labs-Windows/blob/ce74acf608383502e42cd903b660d45f281281bb/components/StackedNotificationsBehavior/samples/StackedNotificationsBehaviorCustomSample.xaml#L14-L17

We should instead be able to show this as part of the sidebar of options available for the sample to present these types of actions in a consistent pattern and minimize the XAML to be that which is required for the feature in typical usage.

### Steps to reproduce

```text
N/A
```

### Expected behavior

Proposal:

```cs
[ToolkitSampleButtonAction(string commandName, string buttonLabel, string methodName, bool isVisible = true)]

[ToolkitSampleButtonAction("SendMessage", "Send Notification", nameof(SendNotificationMessage), Title = "Optional Header"]
public sealed partial class MySimpleSample : Page
{
public MySimpleSample()
{
this.InitializeComponent();
}

public void SendNotificationMessage()
{
// Code to run when button is clicked
}
```

This would create a button on the side panel which when clicked would execute the method of the given sample class, in the above `TestMethod`. It would also create a named `SendMessageCommand` which could be leveraged in the sample XAML code for other purposes as well if some embedded UI element also needed a command version of it to trigger in an alternate way or if `isVisible` is set to false to use just as a command but not show in the sidebar.

Don't think there's a better way to connect the method to the attribute... @Sergio0694? I suppose we could put the attribute on the method in the class instead? Would separate it from our other options, but make it clearer and remove the need for `nameof`. Would also make it easier if we wanted to remove that method from the displayed sample code:

```cs
public sealed partial class MySimpleSample : Page
{
public MySimpleSample()
{
this.InitializeComponent();
}

[ToolkitSampleButtonAction("SendMessage", "Send Notification", Title = "Optional Header"]
public void SendNotificationMessage()
{
// Code to run when button is clicked
}
```

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [ ] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

_No response_

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