Restructure the crypto(7) manpage and add authentication algorithms.

Add separate sections for authentication algorithms, block ciphers,
stream ciphers, and AEAD algorithms. Describe properties commmon to
algorithms in each section to avoid duplication.

Use flat tables to list algorithm properties rather than nested
tables.

List implemented authentication algorithms.

Reviewed by: gbe (manpages)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27833