fix: Enhance extraSettings handling and fix XML output

[Chartman123]

This fixes#1469

The getExtraSettings() function now returns an associative array so that the XML response of the API is working again.

Furthermore, we now store only set (true) extraSettings to the DB.

[Chartman123]

Ok, I think I found the reason why the XML output breaks... It's the getExtraSettings() in Question.php that returns an object. I think we must refactor the code to work with an associative array here just like for getAccess() in Form.php

[codecov]

Codecov Report

Merging #1705 (9ff9533) into main (255c908) will increase coverage by 0.28%.
Report is 3 commits behind head on main.
The diff coverage is 80.00%.

❗ Current head 9ff9533 differs from pull request most recent head 40b2bda. Consider uploading reports for the commit 40b2bda to get more accurate results

Additional details and impacted files

@@ Coverage Diff @@## main #1705 +/- ##
============================================
+ Coverage 42.05% 42.33% +0.28% - Complexity 568 570 +2 
============================================
Files 55 55 Lines 2385 2388 +3 ============================================
+ Hits 1003 1011 +8 + Misses 1382 1377 -5 

[AlexM4H]

Can someone else possibly review the PR as well, or is there something else preventing the merge?