Migrate scheme parsing and source resolution to a separate lib

**What would you like to be added**:
Migrating most out of what is under `syft/source` into a new project.

**Why is this ~needed~ wanted**:
improve compatibility of objects that encapsulate resolving string descriptions to rich objects such as stereoscope images and file resolvers (potentially not limited to just these two things).

Start by inventorying the existing syft/source package, focusing on scheme parsing and source resolution for stereoscope images and file resolvers. Determine the boundary for the separate project and verify that the migrated objects preserve compatibility with those resolution use cases; the issue does not name specific tests or entry points.

Written by the indexing model from the issue text.