[CT-2464] [Bug] DbtReferenceError again at runtime

[jtcohen6]

We raise a DbtReferenceError at parse time if a private model (access: private) is referenced from outside its group:

dbt-core/core/dbt/exceptions.py

Lines 1165 to 1176 in 6fedfe0

	class DbtReferenceError(ParsingError):
	def __init__(self, unique_id: str, ref_unique_id: str, group: str):
	self.unique_id = unique_id
	self.ref_unique_id = ref_unique_id
	self.group = group
	super().__init__(msg=self.get_message())
	def get_message(self) -> str:
	return (
	f"Node {self.unique_id} attempted to reference node {self.ref_unique_id}, "
	f"which is not allowed because the referenced node is private to the {self.group} group."
	)

Out of an abundance of caution, and to avoid weird edge cases, we should raise it again (or a similar exception) while resolving refs at runtime. Probably within the RuntimeRefResolver.