Add radio group/button example page

[chrisglein]

Radio buttons are a commonly used control for desktop applications (in fact in the WinUI gallery it's categorized as "basic input"). There should be an example in Gallery of how to use them.

There are two main options that present themselves today:

• A) Use a JS-only control like https://github.com/thakurballary/react-native-radio-buttons-group
• B) Use react-native-xaml to access it directly

Would lean towards the former to start with since we already have a RNX page to cover the general concept, but it also wouldn't be bad to include within the page.

[Saadnajmi]

(drive by comment) If using a JS only control, the FURN Radiogroup might be an option

[chrisglein]

(drive by comment) If using a JS only control, the FURN Radiogroup might be an option

I love drive by comments from Saad!
You're right. And it'd be more Fluent than the cross-platform module I used (see #411). As is I provided 2 samples:

1. cross-platform module (not Fluent)
2. react-native-xaml Windows-specific (very Fluent)

FURN would solve both.

Buuuuuut.... to incorporate FURN into Gallery (Which I want to do! Will open an issue from this comment), I think we first need to address these:

• Required explicit importing of SVG (see Some necessary NPM modules are not in dependencies in package.json fluentui-react-native#2613)
• Required switching to classic runtime (see FluentUI in Expo project, pragma and pragmaFrag cannot be set when runtime is automatic fluentui-react-native#1891)
• Updates to the Windows visual theme (see this override)
  (I hit these when developing this: Add fluent-ui-react-native controls and update various visual styles chrisglein/artificial-chat#116)

Maybe we can partner up and fixing these and getting FURN in this Gallery app?