CMS Editor: Handle booleans

[some-molasses]

There's a bug we need to fix around the admin editor.

Steps to replicate:

1. Open http://localhost:3000/admin/editor?page=documents/elections.json
2. Try updating the value of a candidate's elected status (i.e. true -> false)
3. Press save.
4. Note that rather than successfully saving, an error is thrown. If you go into the Network tab of your devtools and look at the response under http://localhost:3000/api/data?path=documents/elections, you'll see why. The backend expected a boolean for elected, but received a string.

This is because the EditorLabelNode only handles strings at the moment. It's our fallback for all non-object data types, so even though the elected is a boolean, we're using EditorLabelNode anyway.

Steps to solve:

Let's make a new EditorNode subclass to handle booleans. Displaying a checkbox input element would work, among other options.

[isobarbaric]

hey, I'd like to help with this issue

[criscreates]

I'd be happy to work on this!! I don't think I have the ability to assign myself to it yet due to permissions tho 💀