[rh:requests] Add handler for requests HTTP library (#3668)

Adds support for HTTPS proxies and persistent connections (keep-alive)

Closes https://github.com/yt-dlp/yt-dlp/issues/1890
Resolves https://github.com/yt-dlp/yt-dlp/issues/4070
Resolves https://github.com/ytdl-org/youtube-dl/issues/32549
Resolves https://github.com/ytdl-org/youtube-dl/issues/14523
Resolves https://github.com/ytdl-org/youtube-dl/issues/13734

Authored by: coletdjnz, Grub4K, bashonly

yt_dlp/networking/__init__.py

@@ -1,4 +1,6 @@
 # flake8: noqa: F401
+import warnings
+
 from .common import (
     HEADRequest,
     PUTRequest,
@@ -11,3 +13,11 @@ from .common import (
 # isort: split
 # TODO: all request handlers should be safely imported
 from . import _urllib
+from ..utils import bug_reports_message
+
+try:
+    from . import _requests
+except ImportError:
+    pass
+except Exception as e:
+    warnings.warn(f'Failed to import "requests" request handler: {e}' + bug_reports_message())