Pkgr marks tarball dependencies as "user_defined"

[Dreznel]

Found while creating "tarball-install" E2E tests.

ellipsis depends on rlang, but as you'll see in the output, rlang is marked as "user_defined" even though it's not defined in Tarballs or Packages. This might be intentional, but it doesn't seem intuitive.

pkgr.yml:

Version: 1
# top level packages

Tarballs:
  - "./tarballs/ellipsis_0.3.2.tar.gz" # depends on rlang

Packages:
  - crayon

# any repositories, order matters
Repos:
  - LOCALREPO: "./localrepo"

Cache: test-cache

Library: "test-library"

Customizations:
  Repos:
    - LOCALREPO:
        Type: source

[Dreznel]

Looking into the code, this ultimately occurs because we sort of took a shortcut with Tarball dependencies by simply adding them to the list of user-defined packages in the CFG file. The dependencies need to be installed before the tarball installation is attempted, and ensured that that would happen without requiring have pkgr do an entirely separate, "from the ground up" installation procedure for tarballs.

This is causing a test to fail at the moment. I am in favor of simply calling this "expected behavior" and updating the test accordingly until we have a chance to come back to this.