[ML] Bedrock Cohere should support embedding_type

[prwhelan]

Request should support one of byte, float, int8 as per https://www.elastic.co/guide/en/elasticsearch/reference/current/infer-service-cohere.html

PUT _inference/text_embedding/multilingual-cohere-v3-search
{
  "service": "amazonbedrock",
  "service_settings": {
    "access_key": "***",
    "secret_key": "***",
    "region": "us-east-1",
    "provider": "Cohere",
    "model": "cohere.embed-multilingual-v3",
    "embedding_type": "float"
  }
}

We currently only support parsing float: AmazonBedrockEmbeddingsResponse

We should be able to reuse this code: CohereEmbeddingsResponseEntity

https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-embed.html

[elasticsearchmachine]

Pinging @elastic/ml-core (Team:ML)