Remove module self-import hacks

A lot of the code in src/editors/ uses this sketchy self-import hack to facilitate mocking and avoid circular import errors. It is bad practice and I think it only works because of webpack black magic. All usage of importing from the current file should be removed.

Example of this import * as module from './(self)' pattern:

https://github.com/openedx/frontend-app-authoring/blob/99e11d3534ddc991c5c01bae42160be4a4ade120/src/editors/containers/ProblemEditor/components/EditProblemView/AnswerWidget/hooks.js#L3-L7

As part of this, we should likely create a new ADR that supersedes ADR 0005 for testing - see some of the principles listed in https://github.com/openedx/frontend-app-authoring/issues/2075

Personally, I (@bradenmacdonald) try to keep mocking to a minimum and instead of mocking out and overriding hooks, just simulate realistic user interactions with the UI. The only hooks that I recommend mocking out are data loading hooks / mutation hooks, and those are easy enough to mock without these self-import hacks.

Start with the self-import example in src/editors/containers/ProblemEditor/components/EditProblemView/AnswerWidget/hooks.js, then inventory the same import pattern throughout src/editors. Review ADR 0005 and the principles in issue 2075 before deciding whether a replacement ADR is needed. Done means the self-import hacks are removed across the editors code and the testing guidance is updated if required.