fix: Properly resubscribe to nested prop changes (backport #622)

[mergify]

This is an automatic backport of pull request #622 done by Mergify.
Cherry-pick of 8f4a08f has failed:

On branch mergify/bp/legacy/3x/pr-622
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	both modified:   src/Uno.Toolkit.RuntimeTests/Tests/NavigationBarTests.cs

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To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[agneszitte]

Close as commit already in branch legacy/3x