Enhanced Axe configuration to ensure compliance with WCAG 2.1 AA requirements (Issue1606)

[miguelvaara]

Reasons for creating this PR

To ensure that WCAG 2.1 AA level requirements are met.

Link to relevant issue(s), if any

• Closes #1606

Description of the changes in this PR

Created a JavaScript object that contains Axe's specifications according to WCAG 2.1 AA-level (wcag21aa) and the object is passed as an argument to the Axe functions that require it.

Known problems or uncertainties in this PR

-

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[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.58%. Comparing base (223ddd2) to head (64e0900).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1607 +/- ## ========================================= Coverage 70.58% 70.58% Complexity 1647 1647 ========================================= Files 32 32 Lines 4321 4321 ========================================= Hits 3050 3050 Misses 1271 1271 ```

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