Allow labels search by exact title

What does this MR do and why?

Search a label by exact title via GraphQL.

We have label search but it performs fuzzy matching. For some cases, we want to ensure only exact matches are returned. This adds title to the labels resolver to be consistent with label.

• title argument and searchTerm is mutually exclusive and cannot be used together.
• if title is used, searchIn is removed (because we're ignoring it)

This includes scoped labels and unscoped. By also adding arguments like includeAncestorGroups one can get multiple labels at different levels of the hierarchy with the same title.

Changelog: added

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How to set up and validate locally

query {
  group(fullPath: "flightjs") {
    labels(title: "bug") { # also can use other args includeAncestorGroups: true, includeDescendantGroups: true
      nodes {
        title
        id
      }
    }
  }
}

query {
  project(fullPath: "flightjs/Flight") {
    labels(title: "bug") { # also can use other arg includeAncestorGroups: true
      nodes {
        title
        id
      }
    }
  }
}

Related to #465547 (closed)