Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFH (r254407, r254960, r255371): misc cleanup
MFH (r255386): make libssh private
MFH (r255369, r255376, r255393, r262530): import OpenPAM Nummularia

Pull in OpenPAM Micrampelis from head. Also merge a few minor module
changes, most importantly support for ECDSA keys in pam_ssh.

Upgrade to OpenPAM Lycopsida.

Vendor import of OpenPAM Lycopsida.