Speed up database usage in specs

MSP-9121

Instead of establishing a connection as needed for each access to the
database, maintain a background connection for the entire suite as is
done for rails specs.  This connection can be suspended by tagging the
example group with `:without_established_connection`, which will
remove the suite connection and re-establish it after all the examples
in the group have run.

This change brought the spec time down from 30 minutes to 12 minutes.
Merge branch 'feature/module-cache-construction' into bug/slow-specs
Document delegate methods

MSP-9121

Added @!method tags for all delegate calls.  Removed
`#module_type_enabled?` because its unused in the new cache.  Updated
YARD in an attempt to get (see ...) syntax to work with @!method tags
(it didn't), but leaving it since YARD should be updated anyway.
Land limhoff-r7#15, slow specs