New VS Code syntax extension

[xpe]

Could you add github.com/xpe/vscode-ron to the README's Tooling section? Or would you like me to start a PR?

I created it this week and published it to the VS Code marketplace. I started from the VS Code Rust syntax grammar as a foundation. My POV is that having more than one extension can help quality, especially when developed from a different starting point than existing implementations.

[juntyr]

Thank you for working on the extension! If you want, you can submit the PR yourself (no CHANGELOG entry would be required for this), otherwise I can add it later.