refactor: consolidate neo4j schema into a single place

[georgesafta]

Motivation and Context

Related to: codellm-devkit/codeanalyzer-typescript/issues/15
Consolidating the Neo4J schema into a single file and generating the DB constraints from the NodeLabel descriptors.

How Has This Been Tested?

• regenerated the Neo4J schema using the CLI: uv run canpy --emit schema > schema.neo4j.json
• executed the Testcontainers integration test: RUN_CONTAINER_TESTS=1 uv run pytest test/test_neo4j_bolt.py -s
• some tests are failing when running uv run pytest on the main branch, so made sure no new failure appear after my changes

Breaking Changes

None

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactor
• Documentation update

Checklist

• I have read the Codellm-Devkit Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Some changes are due to the formatter (the pre-commit hooks)