Code Quality: Added ThemedIcon

[mdtauk]

Resolved / Related Issues This is an ongoing project to try to work on a new ThemedIcon control

To prevent extra work, all changes to the Files codebase must link to an approved issue marked as Ready to build. Please insert the issue number following the hashtag with the issue number that this Pull Request resolves.

• Closes #

Steps used to test these changes

Stability is a top priority for Files and all changes are required to go through testing before being merged into the repo. Please include a list of steps that you used to test this PR.

1. Opened Files ...
2. ...

[files-community-bot[bot]]

✅ Successfully formatted XAML files.

[0x5bfa]

@mdtauk has a separate repo for us to be able to test the control. But the problem is WinUI test project cannot reference WinUI project (#15762) (we definitely don’t want to include test features inside Files.App project). Therefore, we should wrap up everything there and port everything excluding the test window and then merge asap. I’ll try to figure out how to reference the project from an unit test project but this shouldn’t be a blocker against merging.

[0x5bfa]

@marcelwgn as you suggested we decided to create a separate class library for controls (Files.App.Controls) and an unit test project (Files.App.UITests) for that project. To ease PR’s review work, we’ve splitter up work into three: adding template project for both, adding ThemedIcon implementation and its test and lastly replacing the old icons with this icon control. Thank you for reviewing!