Dexpreopt soong modules inside soong

Port the dexpreopt logic from Make to the dexpreopt package in Soong,
and use it to dexpreopt Soong modules.  The same package is also
compiled into the dexpreopt_gen binary to generate dexpreopt scripts
for Make modules.

Bug: 119412419
Bug: 120273280
Test: no differences to dexpreopt outputs on aosp_sailfish system/,
      only expected changes to dexpreopt outputs on system_other
      (.vdex files for privileged Soong modules no longer incorrectly
      contain .dex contents).
Change-Id: Ib67e2febf9ed921f06e8a86b9ec945c80dff35eb