Docs: Add error handling section to submission handling docs

[LeCarbonator]

• [x] React
• [x] Solid
• [x] Vue
• [x] Angular (Feedback appreciated)

This PR adds some code snippets to get users started on the three common types of errors:

• Sync user errors
• Async user errors
• Server errors

The user errors are implemented using form / field validators (with links to the validation guide page). The Server error example is implemented using TanStack Query.