Support using linked schema in place of DB schema for testing purposes

[labkey-jeckels]

Rationale

ONPRC has added a query that depends on the geneticscore module. To get query validation passing, it's easier to fake the table it needs via a linked schema than to fully configure the geneticscore module. However, it's not currently possible to set up a linked schema with the same name as a "real" schema

Related Pull Requests

• 21.7 fb module containerfor mhc onprcEHRModules#283
• Support using linked schema in place of DB schema for testing purposes ehrModules#259

Changes

• Allow dynamic schema providers (like linked schemas) to supply a schema if the primary schema provider opts out (because the module isn't enabled in that container, for example)