Make script field usable in search-a-licious

[alexgarel]

See https://www.elastic.co/guide/en/elasticsearch/reference/8.14/search-fields.html#script-fields

Script field should be defined in the yaml config.

• define the field as other fields
• define the script supporting parameters

The API should support a field_params parameter where I can put parameters for each scripted field I need eg: "field_params": {"field1": {"a": 1, "b": 2}, "field2": …

Those field are available only if we pass the parameters and only in POST search.