Create a NIRI data processing container.

[Nat1405]

Issue Nat1405/niriPipe#10 needs to build a Dockerfile from a single source of truth. It makes sense to store that Dockerfile and Makefile here in gemini_processing.

This issue is to create a Dockerfile that:

• Will be built from a reliable Makefile with the command make
• Installs required dependencies for nat1405/niriPipe
• Quickly installs the latest version of code from the dev branch of nat1405/niriPipe on each build (dev branch for now, possibly main branch later on)
• Works on both Arcade and Batch
• Can run pytest . fairly easily from GitHub actions and my own personal machine.

[Nat1405]

** An important point: this refactoring of the container drops support for both IRAF and DRAGONS in the same container. It seems to be quite a bit simpler, and possibly a good idea, to split them into two separate containers. However, if the functionality of both IRAF and DRAGONS is desired in a single general-purpose data reduction container, I could probably put that together without too much trouble.