[FEATURE] Add Create Search Pipeline Step

[amitgalitz]

Is your feature request related to a problem?

Implement a create search pipeline provisioning step to create a search pipeline.

Example API request:

PUT /_search/pipeline/my_pipeline 
{
  "request_processors": [
    {
      "filter_query" : {
        "tag" : "tag1",
        "description" : "This processor is going to restrict to publicly visible documents",
        "query" : {
          "term": {
            "visibility": "public"
          }
        }
      }
    }
  ],
  "response_processors": [
    {
      "rename_field": {
        "field": "message",
        "target_field": "notification"
      }
    }
  ]
}

What solution would you like?

We will either expect request_processors and/or response_processors and wont do internal validation for each processor submitted within the step.

use case template step would look like this:

{
    "id": "search_pipeline_1",
    "type": "create_search_pipeline",
    "user_inputs": {
        "name": "my-search-pipeline",
        "description": "some description",
        "request_processors": [
            {
                "filter_query": {
                    "tag": "tag1",
                    "description": "This processor is going to restrict to publicly visible documents",
                    "query": {
                        "term": {
                            "visibility": "public"
                        }
                    }
                }
            }
        ],
        "response_processors": [
            {
                "rename_field": {
                    "field": "message",
                    "target_field": "notification"
                }
            }
        ]
    }
}