fix(schema-compiler): Fix cubes inheritance

[KSDaemon]

This PR fixes a bunch of issues related to cube inheritance. Among them are:

• Pre-aggregations are not inherited via extends in YAML-based models
• Joins are not inherited (when extends is used)
• Cubes using sql_table cant be exented with sql
• AccessPolicy inheritance
• Correct schema validation for inherited cubes

Also included:

• Additional tests for folders
• Additional tests for hierarchies
• Additional tests for accessPolicies
• Tuned schema validator to gather all model errors instead of throwing only the first one. So now, if your model has more then one error - you'll see them all at once instead of fixing them one-by-one.

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Supersedes #8970

Closes #9269, #7137, #8519, #8609, #8970