dns/encrypted-dns-server: Update 0.9.6 => 0.9.21

While here:

• Move crates to Makefile.crates.
• Pass maintainership.
• Backport upstream fix for building without METRICS option. (https://github.com/DNSCrypt/encrypted-dns-server/issues/414)

Commit log:
https://github.com/DNSCrypt/encrypted-dns-server/compare/0.9.6...0.9.21

PR: 294709
Reported by: Evaldas Auryla <ea@uoga.net> (new maintainer)
Approved by: Felix Hanley <felix@userspace.com.au> (old maintainer)
Approved by: osa, vvd (Mentors, implicit)
MFH: 2026Q2