[now-build-utils] Add more complete `PackageJson` typings (#3198)
[now-build-utils] Add more complete `PackageJson` typings (#3198)

* [now-build-utils] Add more complete `PackageJson` typings

Planning on using this in `now-cli`.

* Make "name" optional

* Use a namespace

zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli