Return runner editUrl via GraphQL API

What does this MR do and why?

This change adds the edit web url of a runner to the GraphQL API. The URL will vary according to usage of the API in a Group or Project.

See usage at: !80924 (merged)

query getGroupRunners($groupFullPath: ID!) {
  group(fullPath: $groupFullPath) {
    id
    runners {
      edges {
        editUrl # new field!
        webUrl
        node {
          __typename
          id
        }
      }
    }
  }
}

Screenshots or screen recordings

How to set up and validate locally

1. Having a group with runners
2. Use query above at http://gdk.test:3000/-/graphql-explorer

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 #336405 (closed)