fix: localise DatePickerDay tooltip

[lhernonCisco]

Description

The tooltips for the days in the DatePickerDay were not localised, and were always showing as english, regardless of the specified locale. This change fixes this so that the tooltip always reflects the browser locale.

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots:

Before (If applicable):

After:

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Documentation update
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Other... Please describe:

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[codecov[bot]]

Codecov Report

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

Project coverage is 94.65%. Comparing base (54f4e57) to head (35e9945).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1670 +/- ## ========================================== - Coverage 94.92% 94.65% -0.27% ========================================== Files 134 134 Lines 19435 19436 +1 Branches 3048 3037 -11 ========================================== - Hits 18448 18397 -51 - Misses 987 1039 +52 ```

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