Fix PackagingBase.CopyDepsToZip

CopyDepsToZip() zips direct dependencies with tags implementing
PackagingItem interface.

Previously, it relied on InstallNeededDependencyTag which has a
different meaning.
- InstallNeededDependencyTag tells whether a dependency is required to
  be installed together.
- PackagingItem tells whether a dependency (of PackagingBase) is
  required to be packaged.

With the separation of InstallNeededDependencyTag and PackagingItem,
PackagingBase module can distinguish cases which were not available
before.(I = InstallNeededDependencyTag, P = PackagingItem)

   a (PackagingBase module)
   |
   |`--(I)--> b
   |
   |`--(P)--> c --(I)--> d
   |
    `--(I/P)--> e

a's CopyDepsToZip(): [c, d, e]

Test: m nothing (packaging_test)
Change-Id: I71fce29b19b0f00dc394981bcf4240e9c1041c7a