Chore/rgaa remaining issues

[FranceBe]

Fixes MXP-3236

Accessibility improvements : (see each commit for an easier review)

• Update the gray colors for a better contrast, based on recommendation from RGAA Audit
• Set minimum transition delay to 1sec to avoid animation that is too fast and remove the limit to 5 sec as it did not make sense with the RGAA requirements
• Automatic animation was not working anymore due to an infinite loop of re-renders from a wrongly configured dependency in a useEffect -> This PR fixes this behavior
• Allow user to stop animation by hovering a plan button or selecting it from keyboard + add tests for useButtonAnimation hook
• Automatically stop animation after each plan has been highlighted once (no infinite animation loop)
• Small refactor of the realTransitionTime function to be clearer
• Add missing aria attributes in SVG & modal
• Improve focus & focus-visible css to match our design system
• Add aria-describedby so screen reader can read the content of the "Info" section + improve the Schedule session as well to be correctly focused and read by screen readers
• Update documentation to match new RGAA requirements states for the project
• Fix unused import from src/Widgets/EligibilityModal/index.tsx as TotalBlock has been moved directly into the component Schedule for consistence with screen reading information
• Dedicated hook for Animation instruction that are announced for screen readers + tests

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

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

See analysis details on SonarQube Cloud