openssh: pass ssh context to BLACKLIST_NOTIFY

Fixes: 19261079b743 ("openssh: update to OpenSSH v8.7p1")
Sponsored by: The FreeBSD Foundation

Refine and update blacklist support in sshd

Adjust notification points slightly to catch all auth failures,
rather than just the ones caused by bad usernames.

Modify notification point for bad usernames to send new type of
BLACKLIST_BAD_USER. (Support in libblacklist will be forthcoming soon.)
Add guards to allow library headers to expose the enum of action values.

Reviewed by: des
Approved by: des
Sponsored by: The FreeBSD Foundation

Add refactored blacklist support to sshd

Change the calls to of blacklist_init() and blacklist_notify to be
macros defined in the blacklist_client.h file. This avoids
the need for #ifdef USE_BLACKLIST / #endif except in the
blacklist.c file.

Remove redundent initialization attempts from within
blacklist_notify - everything always goes through
blacklistd_init().

Added UseBlacklist option to sshd, which defaults to off.
To enable the functionality, use '-o UseBlacklist=yes' on
the command line, or uncomment in the sshd_config file.

Reviewed by: des
Approved by: des
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7051

Revert r301551, which added blacklistd(8) to sshd(8).

This change has functional impact, and other concerns raised
by the OpenSSH maintainer.

Requested by: des
PR: 210479 (related)
Approved by: re (marius)
Sponsored by: The FreeBSD Foundation

Add blacklist support to sshd

Reviewed by: rpaulo
Approved by: rpaulo (earlier version of changes)
Relnotes: YES
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D5915