pytests: add dns_aging, embracing and extending ageing tests
This incorporates tests from various dns*.py files, but makes them
correct.
All but one of these tests pass against Windows 2012r2.
Further patches will remove the broken tests in other files, and fix
Samba so it passes these.
Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Jun 11 09:29:23 UTC 2021 on sn-devel-184