Edit form HOC refactor

[camdendotlol]

Summary

This PR addresses an issue exposed (but not caused) by the Clerk migration where the edit forms were being defined by a stack of HOCs and HOC-style hooks whose component definitions were not stable when the parent component re-rendered, meaning the form would get remounted every time its parent re-rendered. This never came up before the Clerk migration, because there was nothing that would cause the forms to re-render prior to the user clicking save. But Clerk refreshes its token periodically, causing ClerkProvider (and all its children) to re-render. This meant that these fragile HOC-based forms would periodically unmount, resetting their state including unsaved user input.

The refactor includes copying EditContainer and EditPage from react-components to the CD codebase. Since this is a pretty dramatic change to the code and also the API surface of those components, I decided it wasn't worth taking the time to do a bunch of refactoring on the RC side yet.

This PR also includes a few changes to make the Clerk authentication logic more robust.

[blms]

This looks great!

Could we open an issue, either here or in react-components, for propagating the necessary changes there (and for pulling out any code from here that would be duplicated)—including a basic outline for what needs to be done? Just want to make sure it stays on our radar.