Add logic to get file system dependencies

These deps will be categorized to deps, multilib,... later.

This CL also merges product_config_to_bp.go to filesystem_creator.go

Test: CI and manually compared the dependencies with what's
      in the cf system image bp
Bug: 368364861
Change-Id: Icebcc806a8c9d596d765e9887aa3a8ae477c22a0