[Epic] Convert enzyme tests to react testing library

[chandlerprall]

A discussion was brought up through the effort to support React 17 (#5584) that we will likely need to find a new testing framework to replace Enzyme, as those tests are supportable right now only through a forked enzyme adapter which will not work at all starting in React 18.

In response, we've decided to begin moving existing enzyme tests to react testing library, and once enabled we will author new tests in RTL right away.

First steps

• [Testing] enable react testing library in jest #5597
• team adopts and documents patterns around RTL
• ensure documentation and our adoption around RTL vs Cypress exists

Conversion

NB: converting an enzyme test to cypress instead of RTL, when it makes sense, is acceptable

put list of test files with enzyme tests here