Handle pending events properly
Context: https://gitlab.gnome.org/GNOME/fractal/-/merge_requests/924#note_1333516.
We currently show pending events by creating "fake" events with a bogus event ID, which works for messages with only text content but doesn't work for attachments as we don't have a URI yet.
I believe the cleanest way to handle that would be having two types (the current Event
, and a new PendingEvent
) that would subclass the same type so it's handled transparently by the timeline. It could also allow us to handle #772 with a new type.