bug(mat-date-range-picker): In windows high contrast mode, focus indicator is not present for selected dates

[sourabhsoni0711]

Reproduction

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• Components: https://stackblitz.com/fork/components-issue
• Harnesses: https://stackblitz.com/fork/harness-issue

Steps to reproduce:
1 .Enable High contrast mode in windows machine
2. Open date range picker in example 1 https://material.angular.io/components/datepicker/examples
3. Observe that 'selected date' and 'Down pointing arrow' are not visible in HC mode and does not have focus indicator.

Expected Behavior

In HC mode, all the elements should be visible and also visible focus indicator should be present for all controls

Actual Behavior

'Down pointing arrow' is invisible and the 'selected dates' does not have a visible focus indicator.

Environment

• Angular: 11.0.3
• CDK/Material: 11.0.3
• Browser(s): Firefox 88
• Operating System (e.g. Windows, macOS, Ubuntu): Windows 10 Enterprise

[crisbeto]

I'm submitting a fix for the focus indication on selected dates. The issue with down arrows is known and it's something that we'd have to tackle across the entire project.

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