[Transform] Add support for lookup type in Runtime mappings 

**Describe the feature:**

Currently, [lookup type](https://www.elastic.co/guide/en/elasticsearch/reference/8.3/runtime-retrieving-fields.html#lookup-runtime-fields) is not supported in the JSON editor for runtime mappings in Transform, Data Frame Analytics, etc. We should evaluate if support can be added.


**Describe a specific use case for the feature:**
