AnimatedIcon won't update Foreground while unloaded

### Describe the bug

AnimatedIcon won't update Foreground while unloaded, leaving the previous color after it is reloaded

### Steps to reproduce the bug

I have an AnimatedIcon in a Page with enabled caching.
If the user navigates to a new page, changes theme and navigates back, the AnimatedIcon will still use the previous foreground.
I guess that the best solution would be to update the color on Loaded?

### Expected behavior

AnimatedIcon Source Foreground is properly updated when the control loads again.

### Screenshots

_No response_

### NuGet package version

WinUI 3 - Windows App SDK 1.6.0: 1.6.240829007

### Windows version

_No response_

### Additional context

_No response_

Start at the AnimatedIcon control and its Loaded lifecycle handling, then reproduce the cached-page, theme-change navigation described in the issue. Trace how Source.Foreground is applied before and after reload. Done means the control shows the current foreground after reload, with regression coverage for this scenario.

Written by the indexing model from the issue text.