Add CI pipeline for automatic tests and compilation against LinuxCNC

[zarfld]

Related to #34

Add CI pipeline for automatic testing and compilation against LinuxCNC and PoKeysLib.

• Add .github/workflows/ci.yml to define the CI pipeline.
  • Include steps for installing LinuxCNC and PoKeysLib.
  • Include steps for installing dependencies.
  • Include steps for compiling the code using CMake.
  • Include steps for running tests.
  • Set the pipeline to trigger on push and pull request to the main branch.
• Add ci-prerequisites.sh for installing required packages for the CI pipeline.
• Modify prerequisites.sh to remove installation of packages now handled by ci-prerequisites.sh.

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