[PYG-53, PYG-55, PYG-47] Query across direct relations

[doctrino]

Description

Please describe the change you have made.

Checklist:

• Tests added/updated.
• Documentation updated.
• Changelog updated in CHANGELOG.md.
• Version bumped. If triggering a new release is desired, bump the version number in
  version.py and
  pyproject.toml per semantic versioning.
• Regenerate example SDK export PYTHONPATH=. && python dev.py generate. Need to be run both
  for pydantic v1 and v2 environments.