Feat(messages): Edit messages

[DorraJaouad]

☑️ Resolves

• Fix ✏️ Edit message - Frontend #11205

• Editing a message in a group of messages split the group at the edited message.
• After completing edit or aborting it, it should resume the previous input.
• Edit in default input showing the original content as a "quote"
  • Don't allow changing from message to caption and vice-versa
  • Don't allow to toggle silent send on
• System message hidden like with delete?
• Visible indicator a message was edited (and by whom/when)?
  • Amend to the author name (edited) / (edited by moderator-name)
  • Editor+Time in Message menu as subline of timestamp
• Time limitation like for delete?
  • Limit editing to X hours (draft 24 hours, check what others do and discuss again)
  • Set the limit on deletion to infinite
• What to do about mention notifications (added a mention, removed a mention)?
  • Should indicate in the UI what happens (only when affected)
  • Make sure people don't get 1 for the message and 2 for followup edits
• What about bots?
  • Can not edit bot messages, moderators can
  • Bots will not get explicitly notified about previous edits (only with the default system message)?
  • If a message triggered a bot already it's yolo and will not be retriggered with the new content automatically (bot can do based on the system message?)
    • Should indicate in the UI what happens (only when affected)

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

Message	Menu

🚧 Tasks

• Visual review
• Code review

🏁 Checklist

• 🌏 Tested with Chrome, Firefox and Safari or should not be risky to browser differences
• 🖌️ Design was reviewed, approved or inspired by the design team
• ⛑️ Tests are included or not possible
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required

[Antreesy]

Couple of remarks, while you're still working on it

[Antreesy]

So far good