build_log_simplifier.py support to validate that it recognizes every line in a log file
build_log_simplifier.py support to validate that it recognizes every line in a log file

in preparation for having it validate in the future that we're not adding new log messages

This change doesn't yet add recognition of all of the new messages, so we can't enable this flag yet

Bug: 140635374
Test: ./build_log_simplifier.py /tmp/log && echo ok # and see that this still works
Test: ./build_log_simplifier.py --validate /tmp/log && echo ok # and see that this fails
Change-Id: I9e366a1609ca250ab61e6d87dd3e5012d6c54449

AndroidX/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx