This commit adds new API endpoint to get stream email which is
used by the web-app as well to get the email when a user tries
to open the stream email modal.
The stream email is returned only to the users who have access
to it. Specifically for private streams only subscribed users
have access to its email. And for public streams, all non-guest
users and only subscribed guests have access to its email.
All users can access email of web-public streams.
We did not show the streams to subscribe in dropdown in user
profile modal when user is not allowed to subscribe others
even in the user's own profile modal which is not correct.
This commit fixes it to show the streams in dropdown for
user's own profile irrespective of whether user is allowed
to subscribe others or not.
This commit refactors the 'get_subscribed_streams_for_user' function
to return an object with two keys: one for the subscribed streams
and another for the streams the user can subscribe to. The node
tests have been updated accordingly.
Renamed 'get_subscribed_streams_for_user' to 'get_streams_for_user'.
This should cause no functional changes.
This is part of a multi-step effort to move away
from using stream names to reference streams, now
that it's impossible for a user to write a message
with an invalid stream name (since switching to
the dropdown).
We should just accept `subscribed` and `previously_subscribed` fields as
arguments to this function to avoid adding them on the `attrs` object
itself to simplify the type for `ApiGenericStreamSubscription`.
We should always return `boolean` type instead of `boolean | undefined`
type for functions `is_subscribed_by_name`, `is_subscribed`,
`is_web_public` to stay consistent with other similar functions which
have the type of `boolean` like `is_invite_only_by_stream_name` and
`is_web_public_by_stream_name`.
