Deprecate react-unit-test-utils on frontend-app-ora

[diana-villalvazo-wgu]

Rationale

https://www.npmjs.com/package/@edx/react-unit-test-utils is outdated, we should now be using React Testing Library (RTL)

This package was created to ease the transition from enzyme to RTL. It is more effort to maintain tests that rely on it than to rework those tests to use RTL natively.

Removal

https://www.npmjs.com/package/@edx/react-unit-test-utils references will be removed and tests using it will convert to using RTL

https://www.npmjs.com/package/@edx/react-unit-test-utils will need to be archived as well.