Add property for generating dm files

Added product property: PRODUCT_DEX_PREOPT_GENERATE_DM_FILES.
If this property is true, APKs compiled as verify will have the dex
files left compressed and the vdex put in a dm file. The vdex file
and oat files are not copied to system partition in this case.

Bug: 70934104
Test: manual

Change-Id: Ie137e14f14642b803a506162de6db8ac65a43f46