feat: allow moderators to force speaker/grid view for everyone

[DorraJaouad]

☑️ Resolves

• Fix Moderators must be able to force speaker/grid view for everyone #13452

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

🏚️ Before	🏡 After
Screenshot before	Screenshot after

🚧 Tasks

• Set the signaling emission
• Apply the call view restriction
• Separate component for call moderation (taking into consideration future options to be included)
• Improve modal layout (kinda ugly rn)
• Migrate the new component to composition API
• Adjust the signaling attr to default to "none" instead of ""
• disable view changing button for non-moderators

Missing functionalities to add

• Late joiners should have the view enforced if it was emitted before joining
• Hint for participants when the force view mode is on (?)
• Select specific video/screenshare to force on
• Show floating button to stop the force view mode on CallView when it is on (?)

🏁 Checklist

• 🌏 Tested with different browsers / clients:
  • Chromium (Chrome / Edge / Opera / Brave)
  • Firefox
  • Safari
  • Talk Desktop
  • Not risky to browser differences / client
• 🖌️ 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

[nickvergessen]

Just mentioning as I don't see it in the check lists.
The moderator must also be able to force a specific video/screenshare to be looked at. Not only the general grid/speaker toggle.