feat(core): add validation of model files against metamodel

[mttrbrts]

Closes #678

Adds an extra validation step in the ModelManager to validate ModelFile object against the Metamodel definition.

When opting into this feature:

• In strict mode, invalid models will now throw an error.
• In the default non-strict mode, a console warning is printed.

Turn on the feature with a parameter to the ModelManager constructor, e.g.

new ModelManager({ metamodelValidation: true });

Changes

• Adds a new MetamodelException class to report errors found while validating the ModelFile
• Adds a new private function on the BaseModelManager that is used when adding a model file.

Flags

• Ideally, I would have liked to build a separate ModelManager instance purely for this purpose. However, this introduced issues with circular dependencies (a ModelManager would then contain a ModelManager!). This approach mutates the client's ModelManager temporarily; this should be safe if we clean up properly after ourselves.
• We also have to disable validation when adding the RootModel to a ModelManager because it is now a pre-requisite for metamodel validation

Related Issues

• Issue Parsed models are not validated against the metamodel #678

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname