Implement configurator image and 2dlayout routes

[jasperoosthoek]

This pull request implements 2 new functions that are missing:

1. configurator/1/configurator/<ifeatureId>/image: Store the url of an uploaded image in an "image picker" feature
2. configurator/<configurationId>/2dlayout?stepId=<stepId>: Get the list of images show in the configurator for this particular step.

[johannesheesterman]

Hello @jasperoosthoek
Thank you for your first contribution! The changes look great.

There is just one issue with the type declaration of the OverviewGroups. Could you please accept the suggestion, then we can go ahead and merge these changes.

[jasperoosthoek]

@johannesheesterman It is not possible for me to test the complete module on its own in our development environment. I use copied versions of the files. That's why my changes might contain small errors like this. But I'm very committed to switching over to this module in our custom configurators and I will probably add more changes in the near future.

Thank you for the quick review!

[johannesheesterman]

@jasperoosthoek what you could do for local development is keep a cloned version of the Elfsquad configurator library in a sibling directory to a web testing project.

Then in the testing project you can point to this local version, in your package.json, using:

"dependencies": {
    "@elfsquad/configurator": "file:../configurator"
},

Ensure you build the configurator library before running the testing web project, by running the build commands in the Elfsquad configurator library folder:

npm i
npm run build # OR npm run watch