Allow vpaths to bubble up to project from configurations

This allows expressing "use these vpaths if this configuration is present in the project", and placing the vpaths in the same configuration block as the file lists.
Port validation logic to walk the new container hierarchy

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branch : container-validation
Rework validateScopes() to handle arbitrary container hierarchies

--HG--
branch : container-validation
Reuse container class test function with API

--HG--
branch : container-validation
Merge config validation improvements

- virtual paths are now allowed to bubble up to the project configuration, like config maps
- the validation system is rebuilt on the new container API