Migrate referrals pages to React Router (#7454)

* Migrate send referral form to React Router

* Migrate referral details page to React Router

* Refactor ReferralHelp to incorporate above changes

* Elevate referrals code to modules

* Remove legacy code

* Refactor and update tests

src/apps/companies/apps/referrals/router.js

@@ -2,24 +2,12 @@ const router = require('express').Router()
 
 const urls = require('../../../../lib/urls')
 
-const renderReferralDetails = require('./details/controller')
-const {
-  renderSendReferralForm,
-  submitSendReferralForm,
-} = require('./send-referral/controllers')
 const interactionsRouter = require('../../../interactions/router.sub-app')
 const {
   setReferralDetails,
   setInteractionsDetails,
 } = require('./middleware/interactions')
 
-router
-  .route(urls.companies.referrals.send.route)
-  .get(renderSendReferralForm)
-  .post(submitSendReferralForm)
-// the details route needs to go below the send route so that it does not try to handle the send route
-router.get(urls.companies.referrals.details.route, renderReferralDetails)
-
 // Adding an interaction to complete a referral
 // This mounts the interactions sub app on the details route
 router.use(