Added full CMake build support and enabled CI

[xvitaly]

Changes:

• Implemented full CMake support, based on our work:
  • builds, runs unit tests and installs project;
  • generates and exports CMake targets for external projects;
  • generates and exports pkg-config files for external projects;
• Enabled GitHub actions and enabled CI for testing builds and running unit tests.
• Removed no longer needed makefiles. CMake will automatically generate them for all supported platforms.

Build instructions:

cmake -S . -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo -DBUILD_SHARED_LIBS:BOOL=ON -DBUILD_EXAMPLES:BOOL=ON -DBUILD_TESTS:BOOL=ON
cmake --build build

Installation instructions:

sudo cmake --install build

Closes #61.