Add BoolTransition

[dbriard]

What does the pull request do?

The PR add BoolTransition to the list of available transitions.

What is the current behavior?

Currently, there is no BoolTransition.

What is the updated/expected behavior with this PR?

This PR will allow to resolve issues with pane animation, that require to animate IsVisible in a transition.

How was the solution implemented (if it's not obvious)?

BoolAnimator already exist in Avalonia, I just create the BoolTransition class to use it in the same way as other transitions.

public class BoolTransition : Transition<bool>
{
    internal override IObservable<bool> DoTransition(IObservable<double> progress, bool oldValue, bool newValue) => 
        AnimatorDrivenTransition<bool, BoolAnimator>.Transition(Easing, progress, oldValue, newValue);
}

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

None

Obsoletions / Deprecations

Fixed issues

Fixes #16935

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0051714-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]