Store full namespace for last accessed test in test browser
Store full namespace for last accessed test in test browser

Without this, two test scenes with the same name but different namespace
didn't behave as expected (the first instance would always be loaded on
starting the test browser up).

peppy/osu-framework,ZLima12/osu-framework,ppy/osu-framework,ppy/osu-framework,peppy/osu-framework,ppy/osu-framework,ZLima12/osu-framework,peppy/osu-framework,smoogipooo/osu-framework,smoogipooo/osu-framework