Bail out of 404 page when favicon.ico doesn't exist (vercel#50795)

## What?

Anytime you open a Next.js application that doesn't have a `favicon.ico`
you'll notice `/_error` is being compiled because the browser requests
`favicon.ico`. This PR ensures the 404 page is not compiled in
development for that request. It helps a little with compilation speed.

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Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/next/src/server/base-server.ts

@@ -2371,6 +2371,14 @@ export default abstract class Server<ServerOptions extends Options = Options> {
     ctx: RequestContext,
     err: Error | null
   ): Promise<ResponsePayload | null> {
+    // Short-circuit favicon.ico in development to avoid compiling 404 page when the app has no favicon.ico.
+    // Since favicon.ico is automatically requested by the browser.
+    if (this.renderOpts.dev && ctx.pathname === '/favicon.ico') {
+      return {
+        type: 'html',
+        body: new RenderResult(''),
+      }
+    }
     const { res, query } = ctx
     try {
       let result: null | FindComponentsResult = null