[Feature/agent_framework] Add Get Workflow API to retrieve a stored template by workflow id

[joshpalis]

Description

Closes #263 in favor of this PR

Adds a Get Workflow API that retrieves a workflow from the Global Context index. We've decided to instead just rename the Get Workflow State API implementation and keep this and the Get Workflow API separate (separate handlers, separate request response classes, separate transport action handlers). I have updated the RestGetWorkflowAction -> RestGetWorkflowStateAction, GetWorkflowTransportAction -> GetWorkflowStateTransportAction, GetWorkflowRequest -> GetWorkflowStateRequest, etc.

The name RestGetWorkflowAction, GetWorkflowTransportAction will be used for this PR's API

Creating a workflow :

curl -i -XPOST "localhost:9200/_plugins/_flow_framework/workflow" -H "Content-Type:application/json" --data '{"name":"create-connector-register-deploy-model","description":"test case","use_case":"TEST_CASE","version":{"template":"1.0.0","compatibility":["2.12.0","3.0.0"]},"workflows":{"provision":{"nodes":[{"id":"workflow_step_1","type":"create_connector","user_inputs":{"name":"OpenAI Chat Connector","description":"The connector to public OpenAI model service for GPT 3.5","version":"1","protocol":"http","parameters":{"endpoint":"api.openai.com","model":"gpt-3.5-turbo"},"credential":{"openAI_key":"12345"},"actions":[{"action_type":"predict","method":"POST","url":"https://${parameters.endpoint}/v1/chat/completions"}]}},{"id":"workflow_step_2","type":"register_remote_model","previous_node_inputs":{"workflow_step_1":"connector_id"},"user_inputs":{"name":"openAI-gpt-3.5-turbo","function_name":"remote","description":"test model"}},{"id":"workflow_step_3","type":"deploy_model","previous_node_inputs":{"workflow_step_2":"model_id"}}],"edges":[{"source":"workflow_step_1","dest":"workflow_step_2"},{"source":"workflow_step_2","dest":"workflow_step_3"}]}}}'

HTTP/1.1 201 Created
X-OpenSearch-Version: OpenSearch/3.0.0-SNAPSHOT (opensearch)
content-type: application/json; charset=UTF-8
content-length: 38

{"workflow_id":"__uoRowBLOZlW2X2X4im"}

Using the API :

curl -i -XGET "localhost:9200/_plugins/_flow_framework/workflow/__uoRowBLOZlW2X2X4im?pretty"
HTTP/1.1 200 OK
X-OpenSearch-Version: OpenSearch/3.0.0-SNAPSHOT (opensearch)
content-type: application/json; charset=UTF-8
content-length: 2484

{
  "name" : "create-connector-register-deploy-model",
  "description" : "test case",
  "use_case" : "TEST_CASE",
  "version" : {
    "template" : "1.0.0",
    "compatibility" : [
      "2.12.0",
      "3.0.0"
    ]
  },
  "workflows" : {
    "provision" : {
      "user_params" : { },
      "nodes" : [
        {
          "id" : "workflow_step_1",
          "type" : "create_connector",
          "previous_node_inputs" : { },
          "user_inputs" : {
            "version" : "1",
            "parameters" : {
              "endpoint" : "api.openai.com",
              "model" : "gpt-3.5-turbo"
            },
            "credential" : {
              "openAI_key" : "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"
            },
            "actions" : [
              {
                "method" : "POST",
                "action_type" : "predict",
                "url" : "https://${parameters.endpoint}/v1/chat/completions"
              }
            ],
            "description" : "The connector to public OpenAI model service for GPT 3.5",
            "protocol" : "http",
            "name" : "OpenAI Chat Connector"
          }
        },
        {
          "id" : "workflow_step_2",
          "type" : "register_remote_model",
          "previous_node_inputs" : {
            "workflow_step_1" : "connector_id"
          },
          "user_inputs" : {
            "name" : "openAI-gpt-3.5-turbo",
            "description" : "test model",
            "function_name" : "remote"
          }
        },
        {
          "id" : "workflow_step_3",
          "type" : "deploy_model",
          "previous_node_inputs" : {
            "workflow_step_2" : "model_id"
          },
          "user_inputs" : { }
        }
      ],
      "edges" : [
        {
          "source" : "workflow_step_1",
          "dest" : "workflow_step_2"
        },
        {
          "source" : "workflow_step_2",
          "dest" : "workflow_step_3"
        }
      ]
    }
  }
}

Issues Resolved

#170
Part of #88

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[dbwiddis]

Quick look but then I got lost in the file renames and changes. I agree "Get" is poorly named for the status API but I'm not sure what all the new APIs do. Can you summarize quickly in the PR summary/first-comment?