Add notes widget resolver

What does this MR do and why?

This MR implements fetchign work item notes through widgets interface. This allows fetching all notes, user comments only or system notes only.

re #378949 (closed)

Screenshots or screen recordings

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How to set up and validate locally

Sample qraphql query to without a specified limit, which gets 100 discussions:

{
  queryComplexity {
    score
    limit
  }
  project(fullPath: "mass_insert_group__0_1/mass_insert_group__1_1/mass_insert_group__2_2/mass_insert_group__3_2/mass_insert_group__4_1/mass_insert_project_private_1") {
    workItems(iid: "454") {
       nodes {
    		id
        title
        widgets {

          ... on WorkItemWidgetNotes {
            discussions {
              nodes {
                id
                
                notes {
                  nodes {                    
                    id
                    createdAt
                    internal
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

response:

{
  "data": {
    "queryComplexity": {
      "score": 125,
      "limit": 300
    },
    "project": {
      "workItems": {
        "nodes": [
          {
            "id": "gid://gitlab/WorkItem/81435",
            "title": "Omnis quos beatae voluptatem quaerat sunt officia repellat odit.",
            "widgets": [
              {},
              {},
              {},
              {},
              {},
              {},
              {},
              {},
              {
                "discussions": {
                  "nodes": [
                    {
                      "id": "gid://gitlab/IndividualNoteDiscussion/271509ab3e3943b4d68f1f1f49c7a8fff938d53f",
                      "notes": {
                        "nodes": [
                          {
                            "id": "gid://gitlab/Note/37077",
                            "createdAt": "2022-10-31T11:33:20Z",
                            "internal": false
                          }
                        ]
                      }
                    },
                    .......
                   ]
                }
              }
          }
      }
    }
  }
}

Sample qraphql query to that specifies first: 3 discussions:

{
  queryComplexity {
    score
    limit
  }
  project(fullPath: "mass_insert_group__0_1/mass_insert_group__1_1/mass_insert_group__2_2/mass_insert_group__3_2/mass_insert_group__4_1/mass_insert_project_private_1") {
    workItems(iid: "454") {
       nodes {
    		id
        title
        widgets {

          ... on WorkItemWidgetNotes {
            discussions(first: 3) {
              nodes {
                id
                
                notes {
                  nodes {                    
                    id
                    createdAt
                    internal
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

response:

{
  "data": {
    "queryComplexity": {
      "score": 28,
      "limit": 300
    },
    "project": {
      "workItems": {
        "nodes": [
          {
            "id": "gid://gitlab/WorkItem/81435",
            "title": "Omnis quos beatae voluptatem quaerat sunt officia repellat odit.",
            "widgets": [
              {},
              {},
              {},
              {},
              {},
              {},
              {},
              {},
              {
                "discussions": {
                  "nodes": [
                    {
                      "id": "gid://gitlab/IndividualNoteDiscussion/271509ab3e3943b4d68f1f1f49c7a8fff938d53f",
                      "notes": {
                        "nodes": [
                          {
                            "id": "gid://gitlab/Note/37077",
                            "createdAt": "2022-10-31T11:33:20Z",
                            "internal": false
                          }
                        ]
                      }
                    },
                    .......
                   ]
                }
              }
          }
      }
    }
  }
}

MR acceptance checklist

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