Add checkconf tests for [#2463]

Add checkconf tests for [#2463]

Add two tests to make sure named-checkconf catches key-directory issues
where a zone in multiple views uses the same directory but has
different dnssec-policies. One test sets the key-directory specifically,
the other inherits the default key-directory (NULL, aka the working
directory).

Also update the good.conf test to allow zones in different views
with the same key-directory if they use the same dnssec-policy.

Also allow zones in different views with different key-directories if
they use different dnssec-policies.

Also allow zones in different views with the same key-directories if
only one view uses a dnssec-policy (the other is set to "none").

Also allow zones in different views with the same key-directories if
no views uses a dnssec-policy (zone in both views has the dnssec-policy
set to "none").