TODO
# Don't throw an exception (e.g. file not found).
# extension.py -d for dry run to only show logs of what would happen.
# extension.py -o <output-path>.
# extension.py -l <log-level>.
# ExecuteScriptModifier: Also update content instead of just search and replace.
# service_worker.js: Allow name to be specified on command line.
# Consider using argparse.