Create VSCode extension

Not sure if it might be of interest wrapping this in a VSCode extension to make it more straightforward to build and run `xcodegen` projects.

For instance extension could depend on following:

```json
  "extensionDependencies": [
    "sswg.swift-lang",
    "nisargjhaveri.ios-debug"
  ],
  "devDependencies": {
    "xcodegen": "^2.2.0"
```