Proposal: official support of UISettings.ColorValuesChanged

# Proposal: official support of UISettings.ColorValuesChanged

## Summary

Currently the API `UISettings.ColorValuesChanged` works only for specific configurations, but in general it is not supported ([docs](https://learn.microsoft.com/en-us/windows/apps/desktop/modernize/desktop-to-uwp-supported-api#events)). It would be great having the support for the developers of Windows App SDK and MAUI.

## Rationale

1) The feature should be added to ease the developers and to avoid the "tricks" proposed in #9372.
2) UISettings.ColorValuesChanged was introduced with UWP, so it will ease the migration from UWP to new frameworks.

## Scope

| Capability | Priority |
| :---------- | :------- |
| This proposal will allow developers to use ColorValuesChanged as they were used to in UWP | Must |

Start by reviewing the UISettings.ColorValuesChanged API and the linked Windows supported-API documentation, then compare the workaround discussed in issue #9372. Done means developers can use ColorValuesChanged generally, as they could in UWP, for Windows App SDK and MAUI scenarios.

Written by the indexing model from the issue text.