fix keyboard nav on login screen

[aalves08]

Summary

Fixes #12775

Occurred changes and/or fixed issues

• Fix keyboard navigation on login screen
• checkbox is now visibly focusable
• add role="button" to AsyncButton
• Password component is now tabbable
• refactor LocaleSelector component to work with keyboard navigation (login mode only)

Technical notes summary

Areas or cases that should be tested

• Go to the login screen and browse the page with the tab key
• use enter or space key to trigger UI elements on the page

Areas which could experience regressions

Screenshot/Video

Screen.Recording.2024-12-27.at.15.31.14.mov

Checklist

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• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes