CI: Add GitHub Actions workflow

[Risae]

Description

The AppVeyor pipeline currently doesn't produce any artifacts after every CI run. This PR adds a GitHub Actions workflow for the v1.77.3-dev branch which also published release artifacts + tags associated to it. Every commit will trigger a GitHub Actions pipeline that creates the following:

• Debug MSI x86_64
• Debug Portable x86_64
• Release MSI x86_64
• Release Portable x86_64

Having the CI in GitHub also allows users to easily contribute to improve the CI/CD of mRemoteNG.

Motivation and Context

Users should be easily able to test the latest version of mRemoteNG and report any bugs that might occur. With this GitHub Actions workflow this would enable them to download the latest version.

How Has This Been Tested?

• Example CI run: https://github.com/Risae/mRemoteNG/actions/runs/7430993245
• Releases page would look like this: https://github.com/Risae/mRemoteNG/releases
• The GitHub Actions pipeline currently has the following naming scheme: "v1.77.3-dev-${GITHUB_RUN_NUMBER}"
  • This can be changed if a better one is available
• Signing the binaries (part of PostBuild in mRemoteNG.csproj) is currently not implemented, since i don't have the certificate nor the key. It should be easy to implement.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Changed feature (non-breaking change which changes functionality)
• Changed feature (breaking change which changes functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Updated translation

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• All Tests within VisualStudio are passing
• This pull request does not target the master branch.
• I have updated the changelog file accordingly, if necessary.
• I have updated the documentation accordingly, if necessary.