[feat]: Add support to external downloader aria2p (#31500)

* feat: add class Aria2pFD

* feat: create call_downloader function

* feat: a colorful download interface to aria2pFD

* feat: change value name

* Apply suggestions from code review

Co-authored-by: dirkf <fieldhouse@gmx.net>

* Typo in suggestion

* fix: remove unused value

* fix: add not function to return value(0 is normal); add total_seconds to download.eta(timedelta object); add waiting status when hook progress

* fix: remove unuse method ..utils.format_bytes

* fix: be up to flake8

* fix: be up to flake8

* Apply suggestions from code review

* [feat] test external downloader aria2p

* [feat] test external downloader aria2p

* [fix] test_external_downloader.py

* Apply suggestions from code review

Co-authored-by: dirkf <fieldhouse@gmx.net>

* Apply suggestions from code review

Co-authored-by: dirkf <fieldhouse@gmx.net>

* Update test/test_external_downloader.py

Co-authored-by: dirkf <fieldhouse@gmx.net>

* Update test/test_external_downloader.py

Co-authored-by: dirkf <fieldhouse@gmx.net>

* Update youtube_dl/downloader/external.py

Co-authored-by: dirkf <fieldhouse@gmx.net>

* refactoring code and fix bugs

* Apply suggestions from code review

* Rename test_external_downloader.py to test_downloader_external.py

---------

Co-authored-by: dirkf <fieldhouse@gmx.net>

test/test_downloader_http.py

@@ -9,7 +9,11 @@ import sys
 import unittest
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-from test.helper import http_server_port, try_rm
+from test.helper import (
+    FakeLogger,
+    http_server_port,
+    try_rm,
+)
 from youtube_dl import YoutubeDL
 from youtube_dl.compat import compat_http_server
 from youtube_dl.downloader.http import HttpFD
@@ -66,17 +70,6 @@ class HTTPTestRequestHandler(compat_http_server.BaseHTTPRequestHandler):
             assert False
 
 
-class FakeLogger(object):
-    def debug(self, msg):
-        pass
-
-    def warning(self, msg):
-        pass
-
-    def error(self, msg):
-        pass
-
-
 class TestHttpFD(unittest.TestCase):
     def setUp(self):
         self.httpd = compat_http_server.HTTPServer(