Fix NamespacesLinkPaths.newCommentTemplate field to be array of strings

The NamespacesLinkPaths.newCommentTemplate field, added in !189606 (merged), was defined as a String. However it appears that most of the frontend code that would use the value expects it to be a Object[] instead.

Example

For the query

fragment namespaceURLs on Namespace {
  linkPaths {
    newCommentTemplate
  }
}

query getNamespaceLinks {
  user_namespace: namespace(fullPath: "kattie") {
    ...namespaceURLs
  }
  public_group_namespace: namespace(fullPath: "group-public") {
    ...namespaceURLs
  }
  public_project_namespace: namespace(fullPath: "group-public/p1") {
    ...namespaceURLs
  }
  private_group_namespace: namespace(fullPath: "group-private") {
    ...namespaceURLs
  }
  private_project_namespace: namespace(fullPath: "group-private/p1") {
    ...namespaceURLs
  }
}

The expected result is something like

{
  "data": {
    "user_namespace": {
      "linkPaths": {
        "newCommentTemplate": null
      }
    },
    "public_group_namespace": {
      "linkPaths": {
        "newCommentTemplate": [
          {
            "text": "Your comment templates",
            "href": "/-/profile/comment_templates"
          },
          {
            "text": "Group comment templates",
            "href": "/groups/group-public/-/comment_templates"
          }
        ]
      }
    },
    "public_project_namespace": {
      "linkPaths": {
        "newCommentTemplate": [
          {
            "text": "Your comment templates",
            "href": "/-/profile/comment_templates"
          },
          {
            "text": "Project comment templates",
            "href": "/group-public/p1/-/comment_templates"
          },
          {
            "text": "Group comment templates",
            "href": "/groups/group-public/-/comment_templates"
          }
        ]
      }
    },
    "private_group_namespace": {
      "linkPaths": {
        "newCommentTemplate": [
          {
            "text": "Your comment templates",
            "href": "/-/profile/comment_templates"
          },
          {
            "text": "Group comment templates",
            "href": "/groups/group-private/-/comment_templates"
          }
        ]
      }
    },
    "private_project_namespace": {
      "linkPaths": {
        "newCommentTemplate": [
          {
            "text": "Your comment templates",
            "href": "/-/profile/comment_templates"
          },
          {
            "text": "Project comment templates",
            "href": "/group-private/p1/-/comment_templates"
          },
          {
            "text": "Group comment templates",
            "href": "/groups/group-private/-/comment_templates"
          }
        ]
      }
    }
  },
  "correlationId": "01JY3W1M593B17C7DYPXN4288A"
}