Introduce GitHub Actions into our CI/CD operations

[enriozuni]

Description

This pull request adds the GitHub Actions tool into our CI/CD operations. At the moment, we are using the tool Jenkins tool which builds CogniCrypt only on a Linux environment. Now, with Actions, we build CogniCrypt on three operating systems: Windows, Ubuntu, and macOS. Also, we do not need to have a server in order to host the build since GitHub offers them for free when building open-source repositories.

Fixes #454

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• I have performed a self-review of my own code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes