Meta issue: Fix Nextcloud apps integrations

[ShGKme]

Add talk integration with other Nextcloud apps:

• [ ] Files: Open received files
  • [x] In the beginning - open all files in the default Web-Browser or Web View
  • [x] Open in the default Web-Browser or Web View
    • [ ] Documents (Office)
    • [ ] Contacts
    • [ ] Other files
  • [x] #255
    • [x] Images
    • [x] Videos
  • [ ] #256
    • [ ] PDFs
    • [ ] MDs (texts)
• [x] Files: Send files from Nextcloud (related: https://github.com/nextcloud/nextcloud-dialogs/issues/1)
• [x] User profile - open in the default Web-Browser
• [x] #31
  • [x] ⚠️ Add empty no-op icon quickly so it does not block screencasts
  • [x] Implement notifications afterwards
• [x] #26
  • [x] ⚠️ Add empty no-op icon quickly so it does not block screencasts
  • [ ] Implement status afterwards
• [ ] #30
  • [x] ⚠️ Add empty no-op icon quickly so it does not block screencasts
  • [ ] Implement search afterwards