Fix #6223 - ♿ Accessibility improvements: Month and Year dropdowns

[balajis-qb]

Description

Linked issue: #6223

Problem
As mentioned in the attached ticket, the month select dropdown (showMonthDropdown) and the year select drop down (showYearDropdown) lacks ARIA attributes.

Changes

• Added the corresponding aria attributes to the select and the button element to support the dropdown mode (dropdownMode) of scroll and select
• Added test cases to validate the change

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 99.29%. Comparing base (548a1f3) to head (7f61d82).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6232   +/-   ##
=======================================
  Coverage   99.29%   99.29%           
=======================================
  Files          30       30           
  Lines        3822     3824    +2     
  Branches     1648     1667   +19     
=======================================
+ Hits         3795     3797    +2     
  Misses         26       26           
  Partials        1        1           

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