fix: change target path for nodes defined in yml

[joshuanits]

Resolves #11321

Problem

Models defined in yaml files (such as the new snapshots) are built to a file path such as target/run/models/schema.yml/schema.yml/snapshot.sql.

This is both unclear and introduces possible collisions if target/run/models/schema.yml is a file.

This path is made from joining the file path models/schema.yml with the 'logical' path schema.yml/snapshot.sql.

Solution

If the basename of the file path matches the dirname of the logical path, construct a new path from:

• dirname of the file path models/
• dirname of the logical path, replacing . with _: schema_yml/
• basename of the logical path: snapshot.sql

Joined result being models/schema_yml/snapshot.sql

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.