Unified build on Github for Docker, Linux, macos_arm64, macos_x86_64, windows

This is a prerelease version which does not include the Chombo solver - which has multiple nonstandard builds. The focus of this version is to create a good baseline for future work on individual solvers on multiple platforms (Docker, Linux, macos_arm64, macos_x86_64, windows). All builds use CMake and target LLVM toolchains.