Include flag_check hook for "packages/SystemUI"

Parse arguments in flag_check.py.

- msg = commit message
- files = modified files paths
- project = repo_path

Using project we can filter further for "frameworks/base" and see if
files starts with "packages/SystemUI" and then apply Flags check.

Bug: 306262821
Test: Manual
Flag: NA
Change-Id: I9b678344512527ec8b79aa458dae9f54fb4c61ba