tests: Add a sub-set of tests to show the restored DC is sound

tests: Add a sub-set of tests to show the restored DC is sound

+ Add a new ldapcmp_restoredc.sh test that asserts that the original DC
backed up (backupfromdc) matches the new restored DC.
+ Add a new join_ldapcmp.sh test that asserts we can join a given DC,
and that the resulting DB matches the joined DC
+ Add a new login_basics.py test that sanity-checks Kerberos and NTLM
user login works. (This reuses the password_lockout base code, without
taking as long as the password_lockout tests do). Basic LDAP and SAMR
connections are also tested as a side-effect.
+ run the netlogonsvc test against the restored DC to prove we can
establish a netlogon connection.
+ run the same subset of rpc.echo tests that we do for RODC
+ run dbcheck over the new testenvs at the end of the test run

Signed-off-by: Tim Beale <timbeale@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>