fix(tab-button): nested interactives are not rendered

[liamdebeasi]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
  • Some docs updates need to be made in the ionic-docs repo, in a separate PR. See the contributing guide for details.
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue URL: resolves #23332

This is the same issue as #26575.

What is the new behavior?

• aria-selected and role states on ion-tab-button have been moved to the native <a> inside of the Shadow DOM.
• aria-disabled has been added so screen readers can indicate that the tab button is disabled (This is a bug I discovered while fixing the original issue)
• ariaLabel on ion-tab-button is now inherited to the native <a> element.
• Added a11y test for tab button

Note: This has the same tradeoffs as #26575 re: Chrome + VoiceOver on macOS.

Does this introduce a breaking change?

• Yes
• No

Other information

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