Pass cookies to the aria2c and requests downloaders

For aria2c I've simplified the operation by offloading most of the work for creating a cookie header by just re-doing what Python-requests does. This results in the exact same cookies Python-requests would have used in a requests.get() call or such. It supports multiple of the same-name cookies under different domains/paths based on the URI of the mock request.

devine/core/manifests/hls.py

@@ -428,6 +428,7 @@ class HLS:
                     uri=urljoin(segment.base_uri, segment.uri),
                     out=out_path,
                     headers=headers_,
+                    cookies=session.cookies,
                     proxy=proxy,
                     silent=attempts != 5,
                     segmented=True