Add INP to GA4 with LoAF attribution

[pereirinha]

Adds support for INP

Tasks

• Adds INP metrics
• Bumps Web Vitals to 4+ so that we can leverage the LoAF attribution
• Removes FID
• Remove GA3 logic

Describe the Approach

• Uses the newly added LoAF lib from Web Vitals to collect attribution information

Release Checklist

• Review the release guidelines in the contribution documentation.
• Update the plugin Version: header value in site-performance-tracker.php.
• Confirm that automated tests are passing for this pull request.

[mehigh]

Tested this out, and for the sake of not storing data that's not as useful, I'll trim the delay values to not have decimals after the milliseconds and then will merge it in