[Feature Request] Allow multiple highlights on one field

[christophegachet]

Is your feature request related to a problem? Please describe

I would like to highlight several times the same field using different highlighter types in the same query.
Depending on the search terms, using different highlight algorithm could return more or less relevant highlighting.
I would be able to check the quality of the different highlight results and chose the better.
Today, it's not possible to define several highlights on the same field, only one is taken into account

Describe the solution you'd like

An expected proposal could be

"highlight": {
    "fields": [
      {
        "fulltext.fvh": {
          "number_of_fragments": 10,
          "type": "fvh",
           "matched_fields": [
            "fulltext"
          ]
        }
      },
      {
        "fulltext.unified": {
          "number_of_fragments": 10,
          "type": "unified",
          "matched_fields": [
            "fulltext"
          ]
        }
      }
    ]
  }

Related component

Search:Query Capabilities

Describe alternatives you've considered

No response

Additional context

No response

[mch2]

@christophegachet This sounds like a reasonable request. Would you like to give this a try and submit a pr?