extract_utils: Add VDEX deodex capabilities for oreo

Oreo introduces new optimized dex files (or vdex). While smali/baksmali
have supported vdex since 2.2.1, you actually have to have the .vdex in
the same location as the .oat or else the smali will fail due to not
finding the .vdex. Copy it (if it exists) and echo a warning since vdex
deodexing is still experimental.

Change-Id: Ic612751be45a8b6e54b8794b426a4d5adbbf13d2