Support <dir>:<file> for LOCAL_JAVA_RESOURCE_FILES

Support the same syntax as LOCAL_TEST_DATA for
LOCAL_JAVA_RESOURCE_FILES to allow placing files at a subdirectory
in the jar file by replacing the / before the first path element
to be included with a :.

Test: m -j checkbuild
Test: out/build-${TARGET_PRODUCT}.ninja is the same
Change-Id: I83f3d45bdd156200308dc7ed0e0fea5d895d37a6