BULL-3229: dockerfile lint job

Note that this job is looking for "Dockerfile" in the api and ui directories. Currently neither have one, so it will always fail right now. You can test the job by copying one of the local dev dockerfiles (such as Dockerfile.be.dev) into the appropriate location and naming it Dockerfile, and running the job. To see the job find an issue, you may need to change something, such as setting the user to root.