Add aria-label to table headers with no title

[Nardol]

Proposed change

Some table headers, especialy in different configurations, has no visible title which produce empty cells.
Empty cells could cause somme issues for screen readers users I.E. NVDA.
Using aria-label attribute for these headers allows having content for screen readers which is invisible on screen, adding an aria-label property to ha-data-table allows to add them on config parts which have empty headers.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion: Format devices, entities, and areas as tables for accessibility #6487
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io