Add unit test for button images in layouts

[molesmoke]

Description of Change

Adds a skipped test for #21548 due to a regression caused by #20949

Issues Fixed

None, somebody else will need to fix the actual issue, but it can at least prevent future regressions

[dotnet-policy-service[bot]]

Hey there @molesmoke! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jeremy-visionaid]

@Foda Hope a device test is helpful, even if I don't know how to fix the actual issue without just reverting previous changes

[mattleibow]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 3 pipeline(s).

[mattleibow]

I removed the skip so we can see if our latest changes have fixed it. Namely: https://github.com/dotnet/maui/pull/21737

[mattleibow]

/azp run

[mattleibow]

Forgot to run the tests

[azure-pipelines[bot]]

Azure Pipelines successfully started running 3 pipeline(s).