Add shared templates for the named.conf options plumbing

Add shared templates for the named.conf options plumbing

Almost every test instance's options block starts with the same seven
statements varying only in the instance address: the source-address
trio, port, pid-file, and the listen-on pair. Provide them as jinja2
partials in _common/options/ plus two umbrellas built on the
auto-injected per-instance `ns` variable: options.conf.j2 for the
v4-only case and options-dual.conf.j2 for dual-stack instances.

The partials carry no indentation of their own: consumers pull them in
with {% include_indented %} at the desired depth, so the templates do
not hardcode the block structure they are used in.

Semantic options (recursion, dnssec-validation, notify, allow-*) stay
in the individual config files by design.

Assisted-by: Claude:claude-fable-5