Add approvalProjectRuleDelete mutation

What does this MR do and why?

Add approvalProjectRuleDelete mutation

Takes id of the approvalProjectRule to be deleted. Returns the deleted approval rule if if successful.

Closes #441290 (closed)

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Before	After

How to set up and validate locally

In the graphql explorer:

Replace id with an approval project rule ID for your GDK using the following

---

query {
  project(fullPath: "Flightjs/flight") {
    branchRules {
      nodes {
        approvalRules {
          nodes {
            id
          }
        }
      }
    }
  }
}

If you can't find one with the previous snippet you can generate your own by following this format

gid://gitlab/ApprovalProjectRule/#{approval_project_rule_id}

---

mutation {
  approvalProjectRuleDelete(input: { id: "gid://gitlab/ApprovalProjectRule/4" }) {
    approvalRule {
      id
      name
      type
      approvalsRequired
      eligibleApprovers {
        nodes {
          id
          username
          email
        }
      }
    }
  }
}