Helper script for running TransactionFlinger CUJs

Includes Perfetto collection, IPowerStats, and simpleperf dumps

This doesn't yet try to do anything fancy like disable background
services or lock clocks in order to stabilize measurements, but should
be cool enough for a smoke test

Bug: 405591499
Flag: EXEMPT test only
Test: run script
Change-Id: Ia4dcc8939cda6323bbc57accf920f2bad1c6d6e3