Tweak playwright tests

[max-nextcloud]

Extracted from #7621

• split setOnline and setOffline
• add offline fixture to playwright
• get request token from /csrftoken
• split request token fixture from random user
• cleanup unused type and context
• mimetype change in playwright
• basic editor page object model
• file class for handling uploaded file
• file.open()
• with file.move() and file.close()
• with editor.typeHeading()
• change mimetype both ways
• store test-results folder as artifacts
• move File class to separate file
• use EditorSection in offline test
• chore(test) .withOpenMenu() to access submenus
• write offline and come back online
• reduce nesting in offline test
• wait for close request when closing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.96%. Comparing base (9d98aab) to head (46dde73).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7895   +/-   ##
=======================================
  Coverage   45.96%   45.96%           
=======================================
  Files         141      141           
  Lines        3964     3964           
  Branches      747      747           
=======================================
  Hits         1822     1822           
  Misses       1838     1838           
  Partials      304      304           

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