Accept socks5h:// proxy protocol name

[whew]

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Closes #22618. Makes youtube-dl recognize the socks5h protocol string like cURL does.

Before PR:

$ youtube-dl --proxy socks5h://127.0.0.1:9050 --simulate dQw4w9WgXcQ
[youtube] dQw4w9WgXcQ: Downloading webpage
ERROR: Unable to download webpage: <urlopen error Tunnel connection failed: 501 Tor is not an HTTP Proxy> (caused by URLError(OSError('Tunnel connection failed: 501 Tor is not an HTTP Proxy')))

After PR:

$ youtube-dl --proxy socks5h://127.0.0.1:9050 --simulate dQw4w9WgXcQ
[youtube] dQw4w9WgXcQ: Downloading webpage