This PR adds the demos from the WinUI community call (microsoft#384)

* Add samles from demo

* Apply suggestions from code review

Co-Authored-By: Steven Moyes <[email protected]>

* Additional CR feedback adjustments

* Apply suggestions from code review

Co-Authored-By: Steven Moyes <[email protected]>

* Adjust variable name

Co-authored-by: Steven Moyes <[email protected]>

updates winui prerelease version (microsoft#383)

Add links to ItemsRepeater page (microsoft#370)

* Fixing dark mode issue

* Adding more links to ItemsRepeater page

* Merging with master, fixing links

Switch namespaces in teachingtip sample to muxc (microsoft#371)

Resolves 86 code style rule violations. (microsoft#362)

* Resolves all violations of rule IDE0049.

* Resolves 28 violations of rule IDE0019.

Fixing dark mode issue (microsoft#361)

FIx CI test failures because of switch to NumberBox (microsoft#347)

FIx CI test failures because of switch to NumberBox (microsoft#347)

FIx CI test failures because of switch to NumberBox (microsoft#347)

Add missing windows version (microsoft#352)