Feature/3532/federated invitation handling

[mahibi]

resolve #3532

🖼️ Screenshots

federation_invitations_20240221.mp4

Opening the room etc will be done in seperate PR's, so opening the conversation list after accepting the invite is fine for now.

How to test (for now)

1. have 2 users on sermo e.g. userA and userB
2. login with userA on web
3. login with userB on android (make sue push messages can be received)
4. as userA on web:

• create a new group conversation without users
• add userB as federated user (see "Add federated users" section):
  

on android the invitation should pop up as push message. As long the invite is not accepted, reloading the conversation should show the infobox.

To test the badge for the account switcher while an invitation is pending, there must be added another nextcloud instance on android.

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔖 Capability is checked or not needed
• 🔙 Backport requests are created or not needed: /backport to stable-xx.x
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	79	79
Errors	8	8

SpotBugs

Category	Base	New
Bad practice	6	6
Correctness	8	9
Dodgy code	112	109
Internationalization	3	3
Malicious code vulnerability	3	3
Performance	6	6
Security	1	1
Total	139	137

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/3653-talk.apk



To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud Talk app.