Typing for requests / stream

[novitae]

Adds typing for all the request methods, and streams. Covers:

• Session (all methods + stream)
  
  All the Session.get, Session.post, ... now have the kwargs appearing when you start typing it. The argument method is obviously removed on those.
  
  Typing is also added for the Session.stream method, this time including the argument method.

• AsyncSession (all methods + stream)
  
  Exactly the same as Session.

• requests/__init__.py (all methods + request)
  
  All the get, post, ... includes the params thread, curl_options and debug that the request method supports, in addition to the classical request kwargs.

[mxrch]

Very good contribution, more typing is always appreciated