Add WinUI samples

[ocalvo]

Description

This change adds a git submodule reference to the release 1.1 of WinUI-Samples

List of new samples

Target Release

1.1

Checklist

• [x] Samples build and run using the Visual Studio versions listed in the Windows development docs.
• [x] Samples build and run on all supported platforms (x64, x86, ARM64) and configurations (Debug, Release).
• [x] Samples set the minimum supported OS version to Windows 10 version 1809.
• [ ] Samples build clean with no warnings or errors.
• [x] [For new samples]: Samples have completed the sample guidelines checklist and follow standardization/naming guidelines. Request exception: New samples contain interop code between C++ and C# and cannot follow the folder naming guidance.
• [x] If I am onboarding a new feature, then I must have correctly setup a new CI pipeline for my feature with the correct triggers and path filters laid out in the "Onboarding Samples CI Pipeline for new feature" section in samples-guidelines.md. No new features.
• [x] I have commented on my PR /azp run SamplesCI-<FeatureName> to have the CI build run on my branch for each of my FeatureName my PR is modifying. This must be done on the latest commit on the PR before merging to ensure the build is up to date and accurate. Warning: the PR will not block automatically if this is not run due to '/azp run' limitation on triggering more than 10 pipelines. Request exception: Samples demostrates usage of github actions and azure pipelines and cannot follow the naming guidance.

[ocalvo]

WinUI-Samples is currently internal, if this PR is approved then we will make WinUI-Samples public same as this repo.

[Scottj1s]

The sequence is backwards - WinUI-Samples should be made public first, and only then used as a submodule in another public repo