fix(nextjs): Add tracing extension methods in wrapServerComponentWithSentry (#7567)

Our E2E tests were [failing](https://github.com/getsentry/sentry-javascript/actions/runs/4488942749/jobs/7894376591#step:6:6185) because apparently we don't initialize a client while building a NextJS app. This caused the tracing extension methods to not be added, resulting in `startTransaction` returning `undefined`. Not sure if this is the best way to fix this but it seems to work (h/t @timfish for the fix).

Author: Lms24

packages/nextjs/src/server/wrapServerComponentWithSentry.ts

@@ -1,4 +1,4 @@
-import { captureException, getCurrentHub, startTransaction } from '@sentry/core';
+import { addTracingExtensions, captureException, getCurrentHub, startTransaction } from '@sentry/core';
 import { baggageHeaderToDynamicSamplingContext, extractTraceparentData } from '@sentry/utils';
 import * as domain from 'domain';
 
@@ -11,6 +11,8 @@ export function wrapServerComponentWithSentry<F extends (...args: any[]) => any>
   appDirComponent: F,
   context: ServerComponentContext,
 ): F {
+  addTracingExtensions();
+
   const { componentRoute, componentType } = context;
 
   // Even though users may define server components as async functions, for the client bundles