feat(cmn): keep raw body in requests (#3550)

Minor modification that puts the raw body as a string on the request
object. Useful for applications where the raw body is required rather
than the parsed JSON body as given by bodyParser. For example, this is
useful when verifying GitHub webhooks.
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.changeset/dirty-trees-kneel.md

+---
+'@eth-optimism/common-ts': patch
+---
+
+Minor update to BaseServiceV2 to keep the raw body around when requests are made.

packages/common-ts/src/base-service/base-service-v2.ts

@@ -386,9 +386,17 @@ export abstract class BaseServiceV2<
       const app = express()
 
       // Body parsing.
-      app.use(bodyParser.json())
       app.use(bodyParser.urlencoded({ extended: true }))
 
+      // Keep the raw body around in case the application needs it.
+      app.use(
+        bodyParser.json({
+          verify: (req, res, buf, encoding) => {
+            ;(req as any).rawBody = buf?.toString(encoding || 'utf8') || ''
+          },
+        })
+      )
+
       // Logging.
       app.use(
         morgan('short', {