Some configuration options are not supported in JSON config

Some configuration options are not supported in JSON config:

• VectorLabelOptions:
  • text: we should be able to provide an attribute name that will be used via style expressions
  • style: we should be able to provide a style defined in styles.ts (but as the prototype is different than OL styles, maybe requires a new dictionary), or use a style expressions to avoid using a function
• OlMeshSourceConfig:
  • format: this can be used for GML for instance (see default config); not sure if we can easily/reliably dynamically construct OpenLayers formats by specifing it's name