chore(SessionList): Migrate to NcButton and MDI icon

[mejo-]

Solves minor issues with menubar height, especially on mobile.

🖼️ Screenshots

🏚️ Before	🏡 After

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.38%. Comparing base (e6db745) to head (291119f).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7184      +/-   ##
==========================================
+ Coverage   51.94%   59.38%   +7.44%     
==========================================
  Files         479      478       -1     
  Lines       41457    36736    -4721     
  Branches     1002     1022      +20     
==========================================
+ Hits        21534    21815     +281     
+ Misses      19817    14820    -4997     
+ Partials      106      101       -5     

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[mejo-]

/backport to stable31