fix(overlays): focus trapping no longer includes disabled elements

[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: N/A internal ticket

When a disabled interactive if the first element, the focus trapping module tries to focus that element on tab. Since the element is disabled and not focusable, focus can escape from the overlay.

What is the new behavior?

• Focus trapping excludes elements hidden with the disabled attribute.

Does this introduce a breaking change?

• Yes
• No

Other information