Expose group member roles through graphQL

What does this MR do and why?

Screenshots or screen recordings

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Before	After

How to set up and validate locally

Run following queries in graphql explorer (https://gdk.test:3443/-/graphql-explorer)

query {
  project(fullPath: "flightjs/flight") {
    id
    name
    memberRoles {
      nodes {
        id
        name
      }
    }
  }
}

query {
  group(fullPath: "flightjs") {
    id
    name
    memberRoles {
      nodes {
        id
        name
      }
    }
  }
}

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #426524 (closed)