Add tests for the new regexp pattern.

This PR adds the following tests for the `patternNew` regexp:

- Basic paths:
  - `/pkg.v3`
  - `/user/pkg.v3`.
- Subpackage paths:
  - `/pkg.v3/sub/pkg`
  - `/user/pkg.v3/subpkg`
- Invalid paths:
  - `/a` (missing version)
  - `/a/b` (also missing version)
  - `/a/b/pkg.v3` (extra `b` path element).