Translatable form and schemas.

[dharizza]

Adding support for displaying form in different languages using a particular schema for said language, as part of this I:

• added support in the SchemaRetriever so we can get the schema for a particular language
• updated FormBuilder so that it gets the current language and retrieves the schema for it, if no schema is found, the default is used.

QA Steps

• [ ] Go to /node/add/data the form should work as usual.
• [ ] Create a new schema for another language in schema/collections, for example dataset.es.json
• [ ] Enable language modules in your Drupal site and add one extra language, for example spanish
• [ ] Go to /en/node/add/data the form should look as usual
• [ ] Go to /es/node/add/data the form should be displaying the data as specified in the dataset.es.json file.

[dafeder]

@dharizza - are you still interested in working on this? Would you want to update the branch and get tests passing?