Add more dex_preopt properties

Move dex_preopt to dex_preopt.enabled, and add dex_preopt.app_image,
dex_preopt.profile_guided, and dex_preopt.profile.  These values will
be passed back to Make if provided to control dex preopting.

Test: m checkbuild
Change-Id: I54a4b1de697a08be20ab65d2a5dc43ce0046692d