Add Mainline update hook for Pre-reboot Dexopt.

Bug: 311377497
Test: manual - Install an apex and see the hook called.
(cherry picked from https://googleplex-android-review.git.corp.google.com/c/platform/frameworks/base/+/26436891)
Change-Id: I604030f6d5df108bc6632e014ce35ebddb5dfaac
Merged-In: I604030f6d5df108bc6632e014ce35ebddb5dfaac