Continuous integration

The project is set up with GitHub actions for continuous integration. It will build the project on Linux (Ubuntu) with GCC and Clang, and on Windows with cl. It gets built and tested in both Debug and Release modes. Sanitizers are enabled for the Linux build.

The action takes ~4 minutes the first time it runs and ~3 minutes for subsequent runs.

vcpkg install is cached and all targets use ccache. It uses 780MB of cache for vcpkg and ccache uses ~0.4MB for the hello world project and the simple tests.

To reduce the number of runs, you may wish to only build in Release mode for GCC and Debug for Clang.