Correctly display deleted messages with attachments
Displaying deleted messages with attachments has always been funky. It's weird how this was missed, or perhaps it got broken at some point, but anyway it's been fixed now. There's no issue for it though.
- Fix displaying deleted messages by MessageDelegate
- Message bubble width is now correct
- The placeholder text is displayed correctly
- AttachmentLoader is now disabled for deleted messages
- Rework SessionDelegate and CoverPage message text formation
- More function-like structure
- Easier to maintain in the future
- Don't display "attachment markers" with the deleted info text