Add presenter for formatting response

We need something that handles formatting the response for the POST `/bill-runs` endpoint. We use what we did in DEFRA/water-abstraction-ui#2247 as a spec.

app/presenters/supplementary-billing/create-billing-batch.presenter.js

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+'use strict'
+
+/**
+ * Formats the response for the POST `/bill-runs` endpoint
+ * @module CreateBillingBatchPresenter
+ */
+
+function go (billingBatch) {
+  const {
+    billingBatchId: id,
+    regionId: region,
+    scheme,
+    batchType,
+    status
+  } = billingBatch
+
+  return {
+    id,
+    region,
+    scheme,
+    batchType,
+    status
+  }
+}
+
+module.exports = {
+  go
+}

test/presenters/supplementary-billing/create-billing-batch.presenter.test.js

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+'use strict'
+
+// Test framework dependencies
+const Lab = require('@hapi/lab')
+const Code = require('@hapi/code')
+
+const { describe, it, beforeEach } = exports.lab = Lab.script()
+const { expect } = Code
+
+// Thing under test
+const CreateBillingBatchPresenter = require('../../../app/presenters/supplementary-billing/create-billing-batch.presenter.js')
+
+describe('Create Billing Batch presenter', () => {
+  let data
+
+  describe('when provided with a populated billing batch', () => {
+    beforeEach(() => {
+      data = {
+        billingBatchId: 'f1288f6c-8503-4dc1-b114-75c408a14bd0',
+        regionId: '6a472535-145c-4170-ab59-f555783fa6e7',
+        scheme: 'sroc',
+        status: 'processing'
+      }
+    })
+
+    it('correctly presents the data', () => {
+      const result = CreateBillingBatchPresenter.go(data)
+
+      expect(result.id).to.equal(data.billingBatchId)
+      expect(result.region).to.equal(data.regionId)
+      expect(result.scheme).to.equal(data.scheme)
+      expect(result.status).to.equal(data.status)
+    })
+  })
+
+  describe('when provided with unpopulated billing batch', () => {
+    beforeEach(() => {
+      data = {
+        billingBatchId: null,
+        regionId: null,
+        scheme: null,
+        status: null
+      }
+    })
+
+    it('correctly presents the data', () => {
+      const result = CreateBillingBatchPresenter.go(data)
+
+      expect(result.id).to.be.null()
+      expect(result.region).to.be.null()
+      expect(result.scheme).to.be.null()
+      expect(result.status).to.be.null()
+    })
+  })
+})