New experiment improvements

[mrlacey]

Fixes #127

This improves the template for creating a new experiment so that it is more useful and removes possible issues.

[michael-hawker]

Looking great, if we use ProjectTemplate it should auto-relpace on creation, right? That'll make the guidance directly applicable to the locations in the solution which could be handy?

[mrlacey]

I'm inclined to add references to Microsoft.Toolkit.Uwp.UI and Community.Toolkit.WinUI.UI in the appropriate test projects as many of the existing tests in the toolkit reference this for access to helper classes when creating UI related tests.
Any thoughts on this?
Any reason not to?
Any other packages to include by default too?

This goal of doing this is to make it easier for anyone creating an experiment to be able to write tests without having to "faff" with adding multiple packages (in different projects) when this is a common task we can do for them.
This would be as a complement to (but not in directly related to) #132

[mrlacey]

Also now need to update https://github.com/CommunityToolkit/Labs-Windows/tree/i127-NewExperimentImprovements/template in light of #136

[michael-hawker]

I'm inclined to add references to Microsoft.Toolkit.Uwp.UI and Community.Toolkit.WinUI.UI in the appropriate test projects as many of the existing tests in the toolkit reference this for access to helper classes when creating UI related tests. Any thoughts on this? Any reason not to? Any other packages to include by default too?

Sorry, missed this comment. Yes, we should do this for the template as well I guess. I think we had discussed adding some common references so that folks can just remove them. That can be done with #132, which now has a PR open here: #139.