Adds the user ID to the return values for the `/fetch_api_key` and
`/dev_fetch_api_key` endpoints. This saves clients like mobile a
round trip to the server to get the user's unique ID as it is now
returned as part of the log in flow.
Fixes#24980.
To provide a smoother experience of accessing a web public stream,
we don't ask user to login unless user directly requests a
`/login` URL.
Fixes#21690.
Adds request as a parameter to json_success as a refactor towards
making `ignored_parameters_unsupported` functionality available
for all API endpoints.
Also, removes any data parameters that are an empty dict or
a dict with the generic success response values.
For users who are not logged in and for those who don't have
'prefers_web_public_view' set in session, we redirect them
to the default login page where they can choose to login
as spectator or authenticated user.
JsonableError has two major benefits over json_error:
* It can be raised from anywhere in the codebase, rather than
being a return value, which is much more convenient for refactoring,
as one doesn't potentially need to change error handling style when
extracting a bit of view code to a function.
* It is guaranteed to contain the `code` property, which is helpful
for API consistency.
Various stragglers are not updated because JsonableError requires
subclassing in order to specify custom data or HTTP status codes.
