implement reportValidity for reporting proper form validation errors behind config flag

[MichaelWest22]

Description

Adds support for reportValidity instead of just using checkValidity like it currently does. Because this could possible alter existing applications that don't expect their htmx activated forms to report invalid inputs and update the focus to the first invalid input currently in htmx i've put it behind a new config item. This is default browser behaviour so all users should ideally have this config turned on but having it has a config will prevent any change to existing applications while allowing users than want this the option to turn it on.

Also this change also allows disabling the report validity if you use preventDefault in the htmx:validation:failed event.

Also had to ensure that reportValidity only fires on the first invalid input so it focuses the right item.

This could replace PR #3215

Corresponding issue:
#2372

Testing

Added tests to ensure it focuses on the first input as expected with reportvalidity

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded