Refactor dexopt related code to DexOptHelper

This change is a preparation change for moving dex package ealier.
The logic will be used for both flag is on/off, moving the common
code that will be used in both places to helper class, no code logic
is changed.

Bug: 321139675
Test: manual. Install app and launch app

Change-Id: I243afc60f7554d2952247419c531d1da6c7790bd