Support for running tests within docker

[kennsippell]

For tests to pass within docker, it requires
const harness = new TestRunner( { "headless": true, "args": [ "--disable-gpu", "--disable-dev-shm-usage", "--disable-setuid-sandbox", "--no-sandbox", ] });

Is it easy to detect if we are within docker and set these options automatically?
https://github.com/medic/config-muso/issues/599#issuecomment-972382216

@bamatic Would you share the command or yml you use to run muso tests within docker to ensure we can test your scenario here?