Separate CLI from main functionality + housekeep

[Lordfirespeed]

Changes

• Removed ability to log to a file
• Removed copy/pasted submodule + replaced with git submodule
  • Updated README accordingly with contributing instructions
• Tidied up CSProj files + added local user csproj template to README
• Tidied up .gitignore
• Separated CLI from main patcher functionality
• Add necessary files for Unity to recognise the project (allows convenient access to the necessary Unity .dlls)
• Refactored Patcher.Patch
• Refactored IL codegen
• adds MinVer package reference (uses Git tags to figure out current version)
• adds build workflow (only builds .nupkg)
• adds (experimental) publish workflow

Todo

• [x] Add log output file option (Closes #6)
• [x] Add --version command (Closes #7)
• [x] Author the MSBuild module (Closes #3)