♿️ Improve calendar header accessibility by adding screen reader text for week numbers

[balajis-qb]

Closes #3797

Description

As mentioned in the linked issue, the screen readers is currently reading the week names header using the text we set instead of the aria-label.

Changes
I added aria-hidden="true" for all the week number headers and moved the aria-label to the separate sr-only span and added colheader role.

Contribution checklist

• I have followed the contributing guidelines.
• I have added sufficient test coverage for my changes.
• I have formatted my code with Prettier and checked for linting issues with ESLint for code readability.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.12%. Comparing base (e7e26d1) to head (dec68cc).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5731   +/-   ##
=======================================
  Coverage   97.12%   97.12%           
=======================================
  Files          30       30           
  Lines        3374     3374           
  Branches     1427     1423    -4     
=======================================
  Hits         3277     3277           
- Misses         95       97    +2     
+ Partials        2        0    -2     

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