Add internal support for file-like object responses to improve adapter plugin support (#1094)

* Support `requests.response.raw` being a file-like object

Previously HTTPie relied on `requests.models.Response.raw` being
`urllib3.HTTPResponse`. The `requests` documentation specifies that
(requests.models.Response.raw)[https://docs.python-requests.org/en/master/api/#requests.Response.raw]
is a file-like object but allows for other types for internal use.

This change introduces graceful handling for scenarios when
`requests.models.Response.raw` is not `urllib3.HTTPResponse`. In such a scenario
HTTPie now falls back to extracting metadata from `requests.models.Response`
directly instead of direct access from protected protected members such as
`response.raw._original_response`. A side effect in this fallback procedure is
that we can no longer determine HTTP protocol version and report it as `1.1`.

This change is necessary to make it possible to implement `TransportPlugins`
without having to also needing to emulate internal behavior of `urlib3` and
`http.client`.

* Load cookies from `response.headers` instead of `response.raw._original_response.msg._headers`

`response.cookies` was not utilized as it not possible to construct original
payload from `http.cookiejar.Cookie`. Data is stored in lossy format. For example
`Cookie.secure` defaults to `False` so we cannot distinguish if `Cookie.secure` was
set to `False` or was not set at all. Same problem applies to other fields also.

* Simpler HTTP envelope data extraction

* Test cookie extraction and make cookie presentment backwards compatible

Co-authored-by: Mickaël Schoentgen <contact@tiger-222.fr>
Co-authored-by: Jakub Roztocil <jakub@roztocil.co>

httpie/client.py

@@ -104,9 +104,8 @@ def collect_messages(
                     **send_kwargs,
                 )
 
-            # noinspection PyProtectedMember
             expired_cookies += get_expired_cookies(
-                headers=response.raw._original_response.msg._headers
+                response.headers.get('Set-Cookie', '')
             )
 
             response_count += 1