Closes #160 and upgrades our tooling to use the latest stable WinAppSdk 1.4. Any components with a dependency on Microsoft.Graphics.Win2D will need to be updated to the latest 1.1.1 right away, see below for details.

Additional notes

Here's what I've found:

• The Extensions component (no win2d dependency) builds as expected with WinAppSdk 1.4.
• The Animations component (only depends on Extensions, no Win2d) builds as expected with WinAppSdk 1.4.
• The Media component (only depends on Animations and win2d) fails to build after updating to Wasdk 1.4 and depending on any version of Win2d (including the latest 1.1.1).
• Upgrading the Wasdk TargetFrameworks to use windows10.0.22621.0 instead of windows10.0.19041.0 results in successful builds for the Media component under both the net6-* and net7-* tfm.

Regarding how this change affects targeting different versions of Windows for WinAppSdk:

• Overall, this won't cause issues for targeting older versions of Windows, but it will require those who depend on our packages to upgrade their Tfm.
• UWP and Uno are unaffected. Uno.UI and Uno.WinUI don't have a dependency on the Windows SDK, and we aren't targeting or compiling Uno for the Media package (since Uno doesn't support Win2d).
• TargetPlatformMinVersion (17763) and TargetPlatformVersion (19041) are defined for both Uwp and Wasdk here.
• Wasdk has SupportedOSPlatform defined here.
• Microsoft.Graphics.Win2D fail to work with winui after 1.1.0 microsoft/Win2D#943: "Only the TargetFramework was updated to get the latest 22H2 improvements, the MinPlatformVersion is still 17763 to ensure that Win2D still runs downlevel."
• Upgrade to v1.1.0 causes compiler error microsoft/Win2D#936 (comment): "You do not need to change your TargetPlatformMinVersion, that has not changed with the new Win2D release."