[networking] Rewrite architecture (yt-dlp#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 yt-dlp#6325, ytdl-org/youtube-dl#22618, ytdl-org/youtube-dl#28093
- Raise error when using `https` proxy instead of silently converting it to `http`

Authored by: coletdjnz

test/test_download.py

@@ -10,10 +10,7 @@
 
 import collections
 import hashlib
-import http.client
 import json
-import socket
-import urllib.error
 
 from test.helper import (
     assertGreaterEqual,
@@ -29,6 +26,7 @@
 
 import yt_dlp.YoutubeDL  # isort: split
 from yt_dlp.extractor import get_info_extractor
+from yt_dlp.networking.exceptions import HTTPError, TransportError
 from yt_dlp.utils import (
     DownloadError,
     ExtractorError,
@@ -162,8 +160,7 @@ def try_rm_tcs_files(tcs=None):
                         force_generic_extractor=params.get('force_generic_extractor', False))
                 except (DownloadError, ExtractorError) as err:
                     # Check if the exception is not a network related one
-                    if (err.exc_info[0] not in (urllib.error.URLError, socket.timeout, UnavailableVideoError, http.client.BadStatusLine)
-                            or (err.exc_info[0] == urllib.error.HTTPError and err.exc_info[1].code == 503)):
+                    if not isinstance(err.exc_info[1], (TransportError, UnavailableVideoError)) or (isinstance(err.exc_info[1], HTTPError) and err.exc_info[1].code == 503):
                         err.msg = f'{getattr(err, "msg", err)} ({tname})'
                         raise
 
@@ -249,7 +246,7 @@ def try_rm_tcs_files(tcs=None):
                 # extractor returns full results even with extract_flat
                 res_tcs = [{'info_dict': e} for e in res_dict['entries']]
                 try_rm_tcs_files(res_tcs)
-
+            ydl.close()
     return test_template