Allow filtering requirements by work_item IID

What does this MR do and why?

Allow filtering Requirements by work_item_iid.

This is part of Requirements legacy IID being deprecated.

to reproduce locally

Requirements require an Ultimate license.

1. Create some requirements via the UI 👉 http://localhost:3000/flightjs/Flight/-/requirements_management/requirements

2. Find the work_item_iid of each via GraphQL

query { 
  project(fullPath: "Flightjs/Flight") {
    requirements {
      nodes {
        id
        title
        workItemIid
      }
    }
  }
}

3. Do some filtering using those values ✨

Filter for a single work_item_iid:

query { 
  project(fullPath: "Flightjs/Flight") {
    requirements(workItemIid: 45) {
      nodes {
        id
      }
    }
  }
}

or multiple

query { 
  project(fullPath: "Flightjs/Flight") {
    requirements(workItemIids: [45, 47]) {
      nodes {
        id
      }
    }
  }
}

and you can use together with iid which is for legacy requirement object IIDs (the query is an intersection so this query will only return records matching both iid arguments)

query { 
  project(fullPath: "Flightjs/Flight") {
    requirements(workItemIid: 45, iid: 1) {
      nodes {
        id
      }
    }
  }
}

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How to set up and validate locally

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Related to #382138 (closed)