Don't HTML encode quotes in REST API callback, to fix ONKI Selector (Skosmos 3)

[osma]

Reasons for creating this PR

See PR #1705. This is the same fix but for Skosmos 3.

Link to relevant issue(s), if any

n/a

Description of the changes in this PR

• when sanitizing the callback parameter, apply the FILTER_FLAG_NO_ENCODE_QUOTES option which prevents encoding quotes

Known problems or uncertainties in this PR

n/a

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud