Refactor Java metadata: use top-level maven metadata & deprecate scope from PomProperties

Today, when scanning a source repository, including resolving packages from Maven `pom.xml`, Syft uses the metadata type `pkg.JavaArchive`, which is not really representative of what was scanned. These could perhaps use `JavaPomProject` as the top-level metadata.

Additionally, the dependency `scope` is being captured in `JavaPomProperties`, which is not the correct spot for this information -- it should be part of the _relationship_, but this is not being tracked as any part of the relationship today.

Start at source-repository scanning and Maven pom.xml resolution, then locate the metadata definitions for JavaArchive, JavaPomProject, and JavaPomProperties. Determine how dependency relationships are represented and define completion as using top-level Maven metadata while moving scope out of PomProperties into the relationship model.

Written by the indexing model from the issue text.