Prepare frontend-lib-content-components to support editing library components

[bradenmacdonald]

This is a placeholder issue to track some general updates and cleanups that will be useful to make, to lay the groundwork for editing components that live in content libraries (and not just those that live in courses).

• Convert to "buildless"
• Turn on TypeScript support
• Document how to actually use this repo in the course authoring MFE in dev mode, with hot reloading
• Work on cleaning up a bit of the messy code, e.g. implementing more of its feature-based folders ADR or eliminating confusing Redux code entirely

[bradenmacdonald]

In the end, I solved this by moving frontend-lib-content-components into course-authoring, which resolved all of the issues mentioned (except the messy code).