add missing type exports, prevent moving dist files to avoid breaking "npm link" feature

[az0uz]

• Keep build files in the dist directory. Moving them to the root and exposing them from the root in the package.json breaks things when you are using npm link with npm start to test new changes while developing other projects.
• Add missing type exports, some types that are used in publicly accessible APIs are not importable by external users. This PR add them to the exports field in package.json