Options for specifying file to Dockerfile

[yashpatel6]

          The context is different from specifying the path to the Dockerfile though no? Ex. the context is `.` but the Dockerfile can be in `./docker/Dockerfile` (this is the `file` argument for the same step that accepts the `context` argument)

Originally posted by @yashpatel6 in uclahs-cds/package-PipeVal#109 (comment)