Feature/noid/more federation avatars

[mahibi]

This PR will

• show federation avatars in conversation info list
• fix to hide moderation actions on participants when not being a moderator
• remove some legacy code

🏁 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?)

[mahibi]

/backport to stable-19.0

[github-actions[bot]]

Codacy

Lint

Type	master	PR
Warnings	81	81
Errors	10	10

SpotBugs

Category	Base	New
Bad practice	6	6
Correctness	8	8
Dodgy code	110	88
Internationalization	3	3
Malicious code vulnerability	3	3
Performance	6	6
Security	1	1
Total	137	115

[github-actions[bot]]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/3764-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.