Add diagnosis screen and add permission checks in settings

[mahibi]

🖼️ Screenshots

Diagnose button in settings	Diagnose screen	Notification permission warning in settings	Exported markdown

🚧 TODO

• database migration

🏁 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?)

[AndyScherzinger]

LGTM, one thing to decide would be if the diagnosis option should be hidden for branded clients or if the "create issue" option should be hidden. Just mentioning it since they point to our GH repo.

[mahibi]

LGTM, one thing to decide would be if the diagnosis option should be hidden for branded clients or if the "create issue" option should be hidden. Just mentioning it since they point to our GH repo.

done by hiding "create issue"

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	83	83
Errors	8	8

SpotBugs

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

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/3558-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.