Add PAC full checksums

Add PAC full checksums

A paper by Tom Tervoort noted that computing the PAC privsvr checksum
over only the server checksum is vulnerable to collision attacks
(CVE-2022-37967).  In response, Microsoft has added a second KDC
checksum over the full contents of the PAC.  Generate and verify full
KDC checksums in PACs for service tickets.  Update the t_pac.c ticket
test case to use a ticket issued by a recent version of Active
Directory (provided by Stefan Metzmacher).

ticket: 9084 (new)