GitHub actions support

[joseasoler]

Based on https://github.com/lukka/CppCMakeVcpkgTemplate/tree/v11

Features:

• Cross-platform builds for all supported platforms.
• clang-format
• clang-tidy
• Potentially, other static analysis tools.

Depends on #24 and #25

Good example of a CI pipeline: https://github.com/CaptainArbitrary/RimWorldMod/blob/main/.github/workflows/ci.yml