[networking] Rewrite architecture (#2861)

New networking interface consists of a `RequestDirector` that directs
each `Request` to appropriate `RequestHandler` and returns the
`Response` or raises `RequestError`. The handlers define adapters to
transform its internal Request/Response/Errors to our interfaces.

User-facing changes:
- Fix issues with per request proxies on redirects for urllib
- Support for `ALL_PROXY` environment variable for proxy setting
- Support for `socks5h` proxy
   - Closes https://github.com/yt-dlp/yt-dlp/issues/6325, https://github.com/ytdl-org/youtube-dl/issues/22618, https://github.com/ytdl-org/youtube-dl/pull/28093
- Raise error when using `https` proxy instead of silently converting it to `http`

Authored by: coletdjnz

yt_dlp/utils/_deprecated.py

@@ -10,16 +10,16 @@ del passthrough_module
 
 
 from ._utils import preferredencoding
+from ..networking._urllib import HTTPHandler
 
 # isort: split
+from .networking import random_user_agent, std_headers  # noqa: F401
 from ..networking._urllib import PUTRequest  # noqa: F401
 from ..networking._urllib import SUPPORTED_ENCODINGS, HEADRequest  # noqa: F401
-from ..networking._urllib import HTTPHandler as YoutubeDLHandler  # noqa: F401
 from ..networking._urllib import ProxyHandler as PerRequestProxyHandler  # noqa: F401
 from ..networking._urllib import RedirectHandler as YoutubeDLRedirectHandler  # noqa: F401
 from ..networking._urllib import make_socks_conn_class, update_Request  # noqa: F401
 from ..networking.exceptions import network_exceptions  # noqa: F401
-from .networking import random_user_agent, std_headers  # noqa: F401
 
 
 def encodeFilename(s, for_subprocess=False):
@@ -47,3 +47,12 @@ def decodeOption(optval):
 
 def error_to_compat_str(err):
     return str(err)
+
+
+class YoutubeDLHandler(HTTPHandler):
+    def __init__(self, params, *args, **kwargs):
+        self._params = params
+        super().__init__(*args, **kwargs)
+
+
+YoutubeDLHTTPSHandler = YoutubeDLHandler