Pass jars with resources to R8

R8 will parse proguard files out of resources in injars.  Use the jar
with resources instead of the classes jar so that R8 can see the
proguard files.

R8 fails when an input jar contains dex files, so filter out dex files
from the input jar before passing it to r8.

Bug: 195558228
Test: m checkbuild
Change-Id: Ibb870ee9c70470336f542a3b7542dab86716dbf8