firebase.json for differential serving

firebase.json

{
  "hosting": {
    "public": "build",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "/",
        "function": "serve"
      }, {
        "source": "**/!(*.js|*.html|*.css|*.json|*.svg|*.png|*.jpg|*.jpeg)",
        "function": "serve"
      }
    ],
    "headers": [{
      "source": "**/service-worker.js",
      "headers": [{
        "key": "Service-Worker-Allowed",
        "value": "/"
      }]
    }]
  }
}