[stable8] feat(NcAppSettingsDialog): adjust design for new form elements, add section descriptions

[backportbot]

Backport of #7797

Warning, This backport's changes differ from the original and might be incomplete ⚠️

Todo

• Review and resolve any conflicts
• Amend HEAD commit to remove the line stating to skip CI

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[AndyScherzinger]

🙏

[codecov]

Codecov Report

❌ Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.62%. Comparing base (4f35494) to head (ddd5cc4).
⚠️ Report is 5 commits behind head on stable8.

Files with missing lines	Patch %	Lines
...ents/NcAppSettingsSection/NcAppSettingsSection.vue	33.33%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           stable8    #7802      +/-   ##
===========================================
+ Coverage    44.61%   44.62%   +0.01%     
===========================================
  Files          188      188              
  Lines         4707     4710       +3     
  Branches      1226     1226              
===========================================
+ Hits          2100     2102       +2     
- Misses        2512     2513       +1     
  Partials        95       95              

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