Add sync variant for cm_room_past_event

Document the async variant while at that.

changed milestone to %0.0.2

added new-api label

As all is quiet here and there's nothing exciting, let's merge this!

added 9 commits

• bbadcc71...d0f3b364 - 7 commits from branch Librem5:main
• fb093dbd - room: Document cm_room_load_past_events_{async,finish}
• 340a8940 - room: Add method to fetch past events synchronously

Compare with previous version

added 11 commits

• 340a8940...8f2517fa - 9 commits from branch Librem5:main
• c7e503c4 - room: Document cm_room_load_past_events_{async,finish}
• ff87dfa0 - room: Add method to fetch past events synchronously

Compare with previous version

enabled an automatic merge when the pipeline for ff87dfa0 succeeds

merged