[Analytics] GA4 Events for Form Submission

[micahchiang]

Description

Google Analytics should track events around form submission.

Considerations

• Should be completed after #553
• All GA4 submission events are listed in the GA4 analytics migration document in confluence
• vets-website analytics helpers
• VAFSC may need some sort of analytics configuration, whoever is working on this should verify. (i.e. does VAFSC need to import a script tag for GA, or is something like window.dataLayer && window.dataLayer.push sufficient)
• Should be be able to verify locally that events are firing with window.dataLayer.

Tasks

• [ ] Add events to onSubmit functionality completed in #553

Acceptance Criteria

• [ ] Tasks have been complete
• [ ] PR has been merged into main