fixes https://github.com/TryGhost/Product/issues/4102
E.g. you recommend myghostsite.com, while that site redirects all
traffic to [www.myghostsite.com](#):
The redirect causes CORS issues, which means we cannot detect
one-click-subscribe support.
- This is fixed by moving the whole detection to the backend, which has
the additional benefit that we can update it in the background without
the frontend, and update it on every recommendation change.
- This change also fixes existing recommendations by doing a check on
boot (we can move this to a background job in the future).
fixes https://github.com/TryGhost/Product/issues/4005
We no longer use the 'reason' of a recommendation, but allow a flexible
description instead. Because this is a breaking change in the API, we do
this before making this feature GA.
- Added new database utils for renaming a column
- Added new migration to rename the column
- Updated all references in code
