Provide a way to pass in credentials to be used by the module.Storage
when contacting registries.
Remove the mockTLSServer and use a static discovery map pointing to the
http url for tests.
Exporting ModuleStorage allows us to explicitly pass in the storgae
location rather than extracting it out of the getter.Storage interface,
set a UI for communiating actions back to the user, and accepting a
services Disco for discovery.