feat(datetime-button): add selecting interaction support

[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: Internal ticket

What is the new behavior?

• Adds support for selecting either the date/time button and reflecting that selection by highlighting the button text
• Datetime button can now link with a datetime instance
• Datetime button now renders the localized date and time according to the value of datetime.
• Adds tests

Does this introduce a breaking change?

• Yes
• No

Other information

There are a few things that will be addressed separately:

• The overlays are not correctly sized
• preferWheel is not fully supported with the combined date/time wheel picker
• Visual regression tests
• Disabling buttons, customizing buttons, etc

[averyjohnston]

There seems to be something wonky with the time display; if I pick a different date, the displayed hour changes but the selected one in the wheel picker doesn't: https://user-images.githubusercontent.com/90629384/178825253-7d164e5c-8505-4b40-b439-9f0065248bad.mp4