Major overhaul of build pipelines.

Tidied up the dockerfiles used to build OpenZGY with SDAPI, and fixed several questionable hacks. Restructured the build rules to make it possible to build both SDAPI and OpenZGY from the same dockerfile and in the same pipeline. With SDAPI just cloned inside the OpenZGY source tree. This means that both modules will always be the latest version.

Note: SDAPI is not implemented as a submodule because that would mean an unwanted dependency. So you will need two "git clone".