Add test for copy of shared dependencies from template database

Add test for copy of shared dependencies from template database

As 98ec35b has proved, there has never been any coverage in this area of
the code.  This commit adds a new TAP test with a template database that
includes a small set of shared dependencies copied to a new database.
The test is added in createdb, where we have never tested that -T
generates a query with TEMPLATE, either.

Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/YXDTl+PfSnqmbbkE@paquier.xyz