Preserve selected font face after focus changes

[danyalahmed1995]

Summary

Fixes the font face AutoSuggestBox resetting to its previous value, or stale filter text, after a keyboard-selected font is committed and focus later leaves the control.

WinUI restores its cached user query when the suggestion list closes. The existing LostFocus path then treated that programmatic restoration as fresh user input and committed the stale value.

This change distinguishes genuine user edits from programmatic text restoration, preserving the committed font value while retaining the queued selected-suggestion commit introduced by #20255.

Fixes #20353.

Validation

Manually validated with a local CascadiaPackage Debug x64 build:

• Reproduced the reset before the fix.
• Selected Lucida Console from Consolas using keyboard navigation.
• Pressed Enter and confirmed Lucida Console was applied.
• Returned focus to the Font face control and tabbed out again.
• Verified Lucida Console remained selected.
• Verified stale filter text did not return.
• Verified the Crashes when pressing Enter after selecting a font from the font dropdown #20245 crash did not regress.
• Verified Save and Discard changes both work.

[carlos-zamora]

@danyalahmed1995 Thanks for working on this. Looks like there's merge conflicts with main. Once you merge main in, I'll come in and review it. 😊

[danyalahmed1995]

Thanks man , I mistakenly fetched from origin instead of upstream 😅. Should be good now merged main into the branch and verified the build by running the build again

[carlos-zamora]

Thanks for the fix!

Verified this works locally. Also checked if this was an issue we had to worry about in the actions page (action type) but I didn't find the issue there, so we don't have to worry about it.

[danyalahmed1995]

Sounds good