Custom review request fields were pretty broken. We tried to write the

<fieldname>_rich_text= value in requests, but had a bug causing the

wrong key to be generated.
This was also designed in a way that resulted in some inconsistencies

with the rest of the API, with the goal of making things consistent with

the database models. Instead of accepting a text_type= string in

requests, we'd accept a rich_text= boolean, which differed from other

text fields.
The API would still return a custom text_type= value in the extra_data

payload, to help, but that would sit along the rich_text=, and would be

inconsistent when forcing text types.
We now use text_type everywhere. Things are much simpler now.

Unit tests pass.
Tried changing values for a custom field in the UI. Saw that the proper

values were saved to the database, and that they were used as a basis

for rendering when forcing text types in a request.