[indexer] handle database schema version

See Knowledge Graph Core Indexer (gitlab-org&17517) for the complete indexer design.

Problem

The Kuzu Database file, per repository, needs to be tied to a specific schema version.

This is so that down the road we can handle:

• re-indexing if the schema version is outdated
• potentially migrations if we find it worth it to use table altering (https://docs.kuzudb.com/cypher/data-definition/alter/)
• observability

Solution

• The schema version should be tied to the VERSION file (or some configurable file) at compile time.
• We should have a detection if the current DB file is outdated