Depend on PRODUCT_COPY_FILES that are not in images

If0e4b958b3dfaa02771a5da70f970379635f904e made `droidcore` stop
depending on `files` so that installed files from unbuilt images
would not be built.  That also disabled the dependency on installed
files that were not in any image, but the vendor notice file had
overly broad dependencies that caused them to still be built.
Icdb11d3c72b180cd02231e8dc98ae500d6566a98 made the vendor notice
file dependencies less broad, exposing the missing `droidcore`
dependencies.

Track the list of installed device files that are not included in any
image, built or unbuilt, and add them as a dependency for `droidcore`.

Bug: 225187583
Test: m checkbuild
Test: check dependency path to encryptionkey.img
Change-Id: I084158ffb52b353e9a3eca9ad06a68c80d3bd371