Migrate to react testing lib instead of enzyme

[felixmosh]

( what is the feature, or what is it this is PR fixing? )

• Title is human readable, as it will be included directly in CHANGELOG.md when we do a release
• If this is a new user-facing feature, documentation has been added to API.md
• Any dist/ changes have not been committed.

Tests run directly on the source code and all dist changes are computed and committed during Formsy release.

I've migrated all the tests to use react testing lib, in the process found some tests that were false, and testing implementation details.

This will allows as to review adding support for React 18 (enzyme doesn't supports it)

[rkuykendall]

Fantastic work! Not just the massive upgrade, but also the small code improvements peppered throughout.

[rkuykendall]

Thank you for asking me to take a look, it was a pleasure to read.