[Android] Make Flyout footer aware of header/content margin

[emaf]

Description of Change

We were not considering the header and content positioning for the footer when the flyout view was a ScrollView and ViewGroup, but that's something we should always execute. The only extra thing we need to do in that case is set padding, as it was already explained in the code.

Also, re-enable the tests that discovered this issue (originally added by https://github.com/dotnet/maui/pull/19125)

[emaf]

This needs to be rebased on top of main once https://github.com/dotnet/maui/pull/19125 is merged. The only commit this PR should have is https://github.com/dotnet/maui/pull/19303/commits/c07acfba177334f4d8fb4a452d6e67f0777cfd04