Ratings API returns URLs depending in app parameter, but this isn't documented

[diox]

The Ratings detail/list API aren't documented as accepting the app parameter. But because they return URLs to user profiles (user.url), and user profiles URLs do depend on an app, it uses the app parameter if present, falling back to User-Agent if not.

Since user profiles do have links to add-ons, we likely want to keep that behavior and:

1. Document it
2. Modify add-ons frontend to pass the current app to ratings API calls - because otherwise we're using User-Agent, despite it not being part of the cache key for the API, resulting in random behavior.

Example (see the user.url properties, which will differ depending on whether or not you add the app parameter, what your User-Agent is, and whether or not this is served from CDN cache):
https://addons-dev.allizom.org/api/v5/ratings/rating/?addon=awesome-screenshot-plus-&page=1&lang=en-US

┆Issue is synchronized with this Jira Task

[diox]

Modify add-ons frontend to pass the current app to ratings API calls - because otherwise we're using User-Agent, despite it not being part of the cache key for the API, resulting in random behavior.

Not such a big deal, because we only show the URL to the user profile if the page is being viewed by someone with Users:Edit permission (this is because most users don't have a user profile page nowadays). Still, filed #2181 for that part

[KevinMind]

Old Jira Ticket: https://mozilla-hub.atlassian.net/browse/ADDSRV-136