Add token pruning to clients for text expansion query

[kderusso]

Adds the following specification after merging elastic/elasticsearch#102862:

• Optional pruning_config added to the text_expansion query
• New weighted_tokens query

[jimczi]

LGTm, thanks @kderusso

[Anaethelion]

I've left a few questions, other than those it looks good!

[Anaethelion]

In the docs there's this example which doesn't have a value property.

{
  "query": {
    "weighted_tokens": {
      "query_expansion": {
        "tokens": {"2161": 0.4679, "2621": 0.307, "2782": 0.1299, "2851": 0.1056, "3088": 0.3041, "3376": 0.1038, "3467": 0.4873, "3684": 0.8958, "4380": 0.334, "4542": 0.4636, "4633": 2.2805, "4785": 1.2628, "4860": 1.0655, "5133": 1.0709, "7139": 1.0016, "7224": 0.2486, "7387": 0.0985, "7394": 0.0542, "8915": 0.369, "9156": 2.8947, "10505": 0.2771, "11464": 0.3996, "13525": 0.0088, "14178": 0.8161, "16893": 0.1376, "17851": 1.5348, "19939": 0.6012},
        "pruning_config": {
          "tokens_freq_ratio_threshold": 5,
          "tokens_weight_threshold": 0.4,
          "only_score_pruned_tokens": false
        }
      }
    }
  }
}

Isn't that field provided by the SingleKeyDictionnary in which the query is embedded ?

[kderusso]

@Anaethelion Thanks for the input. I wasn't quite sure how to model this SingleKeyDictionary. Does this look better?

[Anaethelion]

Much better! SingleKeyDictionary exactly reflects that layout.

I just noticed you have an AdditionalProperty that probably is not needed since you do not have a map with arbitrary keys to deserialize to. That should be removed otherwise it would allow an arbitrary key:value pair to be sent in the payload.

[kderusso]

Thanks, fixed!

[Anaethelion]

LGTM!