As title.

migrie note:

• If TabViewItem: Respect Background & Foreground APIs microsoft-ui-xaml#3769 is fixed before we ingest the latest MUX, check if The rounded bottom corner on a tab doesn't get colored by the color picker #7133 and Saving the settings.json file creates a shadow on the tab? #8948 are fixed
• Make tab corner overlays update colors microsoft-ui-xaml#5145 may have also fixed The rounded bottom corner on a tab doesn't get colored by the color picker #7133, but I think that's only in 2.7