Make the MacOS app launch experience a bit more idiomatic

[origintopleft]

Currently, in order to run IronyModManager, one would have to find the actual binary, explicitly mark it as executable, and then run it. This doesn't count things like Gatekeeper, which is out of our hands right now.

What I can do is make the initial app launching experience a little bit better in the Mac context. I pre-cooked the necessary support files.

Here are the steps (which can theoretically be done in the build process in the future):

• Rename the folder IMM is currently in (maybe osx-x64 or IronyModManager) to Contents.
• Copy these files to the Contents folder, preserving subfolders:
  • Info.plist - XML file, contains information on things like "where the icon is" and "what's my entrypoint" (kinda like an .rc file from Windows dev)
  • MacOS/run.sh - Entrypoint script, in the correct place in MacOS format. Just cds to the parent app directory and runs Irony like normal.
  • Resources/icon.icns - The Irony Mod Manager icon, in Apple ICNS format.
• Create a parent folder, named IronyModManager, and move Contents into it.
• Rename this new topmost folder to IronyModManager.app.

This method keeps IMM portable and self-contained, but I keep it in my user's Applications folder, where it appears properly on LaunchPad.

This is here in discussions instead of as an issue or a pull request, because I don't really know how to properly organize Visual Studio projects, and the main project team can't really test or accept Mac-specific issues.