Refactor formHelpers.js

Long time coming. 'formHelpers.js' is way too long [Edit: and that's a really unhelpful file name]. I'm going to start working on how to break out this stuff into categories that make sense. My plan is still to have multiple components in a file, just to have files that are more specific to function.

[Edit: And to completely get rid of 'formHelpers.js'.]

Start by reading formHelpers.js and inventorying the functions and components it contains. Group the existing code into function-specific files, then update references and verify that formHelpers.js can be removed entirely.

Written by the indexing model from the issue text.