* refactor: use one script to launch py, js, cc linters
* lint changed files as precommit hook
* fix py linter in GN build
* add overlooked files to linter search path
* chore: fix lint warnings
* chore: another try at python import errors
Looks like the problem is that dbus_mock.py is running as
a script but living in the `lib/` directory where it's part of a
module. Moving it up into the `script/` directory seems to
solve the issue.
