Add option --netrc-location

Closes #792, #963

yt_dlp/options.py

@@ -478,6 +478,10 @@ def _dict_from_options_callback(
         '-n', '--netrc',
         action='store_true', dest='usenetrc', default=False,
         help='Use .netrc authentication data')
+    authentication.add_option(
+        '--netrc-location',
+        dest='netrc_location', metavar='PATH',
+        help='Location of .netrc authentication data; either the path or its containing directory. Defaults to ~/.netrc')
     authentication.add_option(
         '--video-password',
         dest='videopassword', metavar='PASSWORD',