[node] trim down values to only what is required for esbuild wrapping logic (vercel#8260)

The edge runtime context we were providing was necessary to  have `ncc`-bundled code run, but after switching to `esbuild`, we didn't update this list.

This PR trims the values down to only what's necessary for `esbuild`-bundled code to run. It also adds comments about why these values are necessary.

Author: EndangeredMassa

packages/node/src/dev-server.ts

@@ -245,10 +245,12 @@ async function createEdgeRuntime(params?: {
         Object.assign(
           context,
           {
-            __dirname: '',
-            module: {
-              exports: {},
-            },
+            // This is required for esbuild wrapping logic to resolve
+            module: {},
+
+            // This is required for environment variable access.
+            // In production, env var access is provided by static analysis
+            // so that only the used values are available.
             process: {
               env: process.env,
             },