A11y problems on star rating component

[Aniort]

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

hello,
2 a11yf issues on star rating comp. :

• inactive stars must have a sufficient contrast ratio cause they provide a piece of information ('total number of stars):
• there's a title attribute in labels, we need to add also an aria-label attribute with the same content
  that's all folks !

Reduced test cases

https://boosted.orange.com/docs/5.2/forms/checks-radios/#star-rating

What operating system(s) are you seeing the problem on?

Windows

What browser(s) are you seeing the problem on?

Chrome, Firefox

What version of Boosted are you using?

5.2