feat(invitations): Import e-mail participants from CSV 🗒️

[Antreesy]

☑️ Resolves

• Ref Allow to import list of participants #13451
• On top of API feat(invitations): Allow importing CSV email lists #13871

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

🏡 After	🏡 After
	--

🚧 Tasks

• Show invited e-mails in the list
• Another place for 'Import' button?

🏁 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 requiredSigned-off-by: Maksim Sukharev [email protected]

[DorraJaouad]

Buttons location:
Why was it related to lobby? IMO it's better if it is in Moderation section under guest access.

User understanding:
There is no clue on how the file should be (format, structure), we discussed these options:

• Sample file
• Add documentation and add a link in the dialog for that section

File structure
To change the format to exactly match that of "Download participants"

[DorraJaouad]

Show invited e-mails in the list

API is not exposing e-mails upon testing.

Another place for 'Import' button?

Will be kept in Meeting section but under separate subsection

[nickvergessen]

/backport to stable30