Ports that depend on youtube-dl: Depend on yt-dlp

yt-dlp [1] is a youtube-dl fork with additional features and fixes. For
ports that depend on www/youtube-dl switch the dependency to www/yt-dlp.
For ports that have an optional dependency on www/youtube-dl, create a
new OPTIONS_RADIO that includes www/yt-dlp and make it the default.

[1] https://github.com/yt-dlp/yt-dlp

Other changes:

• www/yt-dlp: Turn the symlink option on by default
• www/py-pafy: Fix build when depending on www/yt-dlp

PR: 259944
Reported by: Oleh Vinichenko <moonlapse81@gmail.com>
Reviewed by: diizzy, Oleh Vinichenko <moonlapse81@gmail.com>,

		VVD <vvd@unislabs.com>

Approved by: 0mp, adridg (kde@), rm, tcberner (multimedia@),

		yuri (maintainers)
		acm and nivit (maintainers, timeout)

Differential Revision: https://reviews.freebsd.org/D33090