Deeper integration with xUnit via XunitContext (OSOE-354)

[Piedone]

Deeper integration with xUnit via XunitContext for recording metadata. This can be used to add screenshots and warnings (like about flaky tests). Also see: xunit/xunit#2457 and https://xunit.net/docs/getting-started/v3/whats-new#:~:text=documentation%20page.-,Test%20context,-We%20have%20added

Jira issue