GitLab

Refactor the Unpack method to call a single method to unpack each
resource that has been parsed from the pak file. This allows for more
comprehensive testing, without needing to generate fake pak files.

Also add tests for 3 different common resource unpacking scenarios:
- Non-generated resource
- Generated resource
- Shared generated resource, which should not be unpacked and is
  excluded using the new "excludes" argument.

Bug: 1093405
Change-Id: I566ae9dba493931ca39756706df4239f68437c72
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2254702
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780453}