Inconsistent response return for login()

[UlrikHD]

Currently LemmyHttp.login() is the only function that checks for status code before returning a response object, raising a generic Exception if status code isn't 200. To keep functions consistent across all LemmyHttp functions, I would suggest either removing the status code check and just return the response object (preferably) or raising a more precise exception than the base Exception class.

The problem with the current implementation is that if we get an Exception during login, we can't check the response for more granular error handling, e.g. if login is denied or server is down.