The generation was broken due to the refactoring in several classes (some of them where not properly exported).
Also, trying to generate the NPM package on every build now (to detect issues).
If users are willing to use Typescript to develop scripts for maps, they will need typings for the `WA` object.
This commit creates a new package (@workadventure/iframe-api-typings) that contains only the `iframe_api.d.ts` file.
The file is generated from the build of the front and isolated in this package.
This is necessary because the iframe_api.js file is supposed to always be loaded from WorkAdventure directly (and there is no @workadventure/iframe-api package and there will never be one)
