Import open.mp x64 SampSharp code

[ikkentim]

Import code from https://github.com/SampSharp/openmp-sampsharp-x64-poc/ into this repo.

• Move files from that repo root to this repo root
  • .gitignore
  • Directory.build.props
  • SampSharp.sln
  • SampSharp.sln.DotSettings
• Move these files from taht repo root to src/sampsharp-component
  • build.cmd
  • build.sh
• Move the .editorconfig from this repo to src/legacy and put the .editorconfig from that repo into this repo
• Move all /external from that repo to this repo (including submodules)
• Move all /src from that repo to this repo with the same paths (so src/sampsharp-component etc. should exist in this repo)
• Hook up the builds in the main build scripts in this repo root
• Hook up the workflows in this repo, they have currently placeholder steps. Take inspiration from the 'legacy' workflows.