cpanfile: add dependencies of dump_test_schema.pl
cpanfile: add dependencies of dump_test_schema.pl

The aforementioned script, which is used in the course of patching test
databases, has got two additional dependencies (which in turn depend on
quite a few other new modules), which until now were only mentioned in
a dedicated README file in scripts/ . Put them in the cpanfile where
they belong, wrapped in a dedicated feature so that we do not inflict
them on people who do not want to ever patch test databases.

Ensembl/ensembl-test,Ensembl/ensembl-test