Fixed issue in TypedBinding not being able to support nullable types properly

[jBijsterboschNL]

Description of Change

When using the TypedBinding with a nullable type, an InvalidOperationException("Unable to find target value") was throw incorrectly/unnecessary.

Linked Issues

• Fixes [BUG] Set nullable BindableProperty to null throws Exception #354

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description => a unit test perfectly shows an sample of this fix)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

Nullable types are now properly supported.

[TheCodeTraveler]

Thanks @jBijsterboschNL!!

Just FYI - I updated the generic constraints to better implement this feature without using the Null Forgiving Operator (!).

This is modifies the API which is technically a breaking change, albeit, it should be a small impact with a relatively quick fix:

For example, this:

setter: static (vm, text) => vm.Text = text

becomes

setter: static (vm, text) => vm.Text = text ?? string.Empty

[jBijsterboschNL]

@TheCodeTraveler at first I didn't want to make it a breaking change (had the same idea), but good call to do it like this! Thanks for the quick follow up and merging this thing. Any idea on when this could be released, are there any plans for a new release yet? Thanks in advance!