Add command line wrappers for minimally modified phshift2007 programs

[Liam-Deacon]

This should be a legitimate option for users who wish to stick as closely as possible to the reference implementation of phsh* programs, albeit with their own potential issues owing to naïve compilation using modern compilers without attempting to address highlighted issues, e.g. gfortran -std=legacy -Wall -frecursive -fcheck-bounds.

Due to the complexities of bundling these programs as part of wheel builds, it may only be possible to bundle the compiled phsh* binaries with the docker container image.

This probably involves a few tasks:

• Bundle compiled (& statically linked) phsh binaries with Docker image
• Bundle phsh binaries with wheels
• Extend wrapper interface to allow selection of backend, e.g. f2py or legacy
• Document selection and use