Upgrade Xamarin Version to 5

[romanett]

Proposed changes

Preparation for MAUI Upgrade.

ToDo:

• Check if IOS still works
• Request ReadExternalStoragePermission at Runtime ? (Not shure if this is the cause for the Exception occurring when connecting to a server (Access to the path"/storage/emulated/0/" is denied)

Related Issues

• Need MAUI sample application. #616

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• [] Enhancement (non-breaking change which adds functionality)
• Test enhancement (non-breaking change to increase test coverage)
• Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc.
• I have signed the CLA.
• I ran tests locally with my changes, all passed.
• I fixed all failing tests in the CI pipelines.
• I fixed all introduced issues with CodeQL and LGTM.
• I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• I have added necessary documentation (if appropriate).
• Any dependent changes have been merged and published in downstream modules.

Further comments

[romanett]

@mregen i think we can merge this without further testing as the Samples we're already not fully functional before the Upgrade to xamarin 5. and WinUI works, so the shared library Code is okay.