Semantic_text match_all with Highlighter

[Samiul-TheSoccerFan]

This PR addresses the missing highlighting for semantic_text fields when a match_all query is used. We guide users to use semantic highlighting to view their chunks, but highlighting does not currently return any results with match_all. Highlighting is usually unnecessary for non-inference fields with match_all, but it's essential for semantic_text fields to return the generated chunks. This change ensures those highlighting results are returned as expected.

Test cases:

Only text fields

PUT my-index/
{
  "mappings": {
    "properties": {
      "semantic1": {
        "type": "text"
      },
      "semantic2": {
        "type": "text"
      }
    }
  }
}

POST my-index/_doc/1
{
  "semantic1": "Puggles are pugs and beagles",
  "semantic2": "Chiweenies are chihuahuas and dachshunds"
}


GET my-index/_search
{
  "query": {
    "match_all": {}
  }
}

only inference fields

PUT my-semantic-index/
{
  "mappings": {
    "properties": {
      "semantic1": {
        "type": "semantic_text"
      },
      "semantic2": {
        "type": "semantic_text"
      }
    }
  }
}

POST my-semantic-index/_doc/1
{
  "semantic1": "Puggles are pugs and beagles",
  "semantic2": "Chiweenies are chihuahuas and dachshunds"
}

GET my-semantic-index/_search
{
  "query": {
    "match_all": {}
  },
  "highlight": {
    "fields": {
      "semantic1": {
        "type": "semantic",
        "number_of_fragments": 1
      },
      "semantic2": {
        "type": "semantic",
        "number_of_fragments": 1
      }
    }
  }
}

Both infer and non-inference fields

PUT test-index
{
  "mappings": {
    "properties": {
      "test_field": {
        "type": "semantic_text"
      },
      "non_infer_field": {
        "type": "text"
      }
    }
  }
}

PUT test-index/_doc/doc1
{
  "test_field": "these are not the droids you're looking for. He's free to go around",
  "non_infer_field": "this is a non-inference field"
}

GET test-index/_search
{
  "query": {
    "match_all": {}
  },
  "highlight": {
    "fields": {
      "test_field": {
        "type": "semantic",
        "number_of_fragments": 1
      }
    }
  }
}

Some additional cases

GET my-*/_search
{
  "query": {
    "match_all": {}
  },
  "highlight": {
    "fields": {
      "semantic1": {
        "number_of_fragments": 1
      },
      "semantic2": {
        "number_of_fragments": 1
      }
    }
  }
}

GET my-*/_search
{
  "query": {
    "match_all": {}
  },
  "highlight": {
    "fields": {
      "semantic1": {
        "type": "semantic",
        "number_of_fragments": 1
      },
      "semantic2": {
        "type": "semantic",
        "number_of_fragments": 1
      }
    }
  }
}

// throws error as fields are semantic_text field
GET my-*/_search
{
  "query": {
    "match_all": {}
  },
  "highlight": {
    "fields": {
      "semantic1": {
        "type": "score",
        "number_of_fragments": 1
      },
      "semantic2": {
        "type": "score",
        "number_of_fragments": 1
      }
    }
  }
}