feat(plugins): add req.rawBody for routes

Stripe webhooks endpoints requires to read the raw request body.
https://docs.stripe.com/webhooks#verify-webhook-signatures-with-official-libraries

packages/tests/fixtures/peertube-plugin-test-five/main.js

@@ -9,6 +9,10 @@ async function register ({
   router.post('/form/post/mirror', (req, res) => {
     res.json(req.body)
   })
+
+  router.post('/form/post/mirror-raw-body', (req, res) => {
+    res.json(JSON.parse(req.rawBody))
+  })
 }
 
 async function unregister () {

packages/tests/src/plugins/plugin-router.ts

@@ -80,6 +80,24 @@ describe('Test plugin helpers', function () {
     }
   })
 
+  it('Should mirror the raw post body', async function () {
+    const body = {
+      torso: 'arms',
+      legs: 'feet'
+    }
+
+    for (const path of basePaths) {
+      const res = await makePostBodyRequest({
+        url: server.url,
+        path: path + 'form/post/mirror-raw-body',
+        fields: body,
+        expectedStatus: HttpStatusCode.OK_200
+      })
+
+      expect(res.body).to.deep.equal(body)
+    }
+  })
+
   it('Should remove the plugin and remove the routes', async function () {
     await server.plugins.uninstall({ npmName: 'peertube-plugin-test-five' })