process: move --help and --bash-completeion handling to startExecution

Because they are similar to `--prof-process` and are part of
the execution instead of initialization.
Also move the `getOptionValue` initialization to top scope since
it's used everywhere and add comments about the flags.

PR-URL: nodejs#25262
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/internal/bootstrap/node.js

@@ -18,7 +18,7 @@
 
 const { internalBinding, NativeModule } = loaderExports;
 
-let getOptionValue;
+const { getOptionValue } = NativeModule.require('internal/options');
 
 function startup() {
   setupTraceCategoryState();
@@ -160,18 +160,6 @@ function startup() {
     NativeModule.require('internal/inspector_async_hook').setup();
   }
 
-  getOptionValue = NativeModule.require('internal/options').getOptionValue;
-
-  if (getOptionValue('--help')) {
-    NativeModule.require('internal/print_help').print(process.stdout);
-    return;
-  }
-
-  if (getOptionValue('--completion-bash')) {
-    NativeModule.require('internal/bash_completion').print(process.stdout);
-    return;
-  }
-
   // If the process is spawned with env NODE_CHANNEL_FD, it's probably
   // spawned by our child_process module, then initialize IPC.
   // This attaches some internal event listeners and creates:
@@ -376,6 +364,18 @@ function startExecution() {
     return;
   }
 
+  // node --help
+  if (getOptionValue('--help')) {
+    NativeModule.require('internal/print_help').print(process.stdout);
+    return;
+  }
+
+  // e.g. node --completion-bash >> ~/.bashrc
+  if (getOptionValue('--completion-bash')) {
+    NativeModule.require('internal/bash_completion').print(process.stdout);
+    return;
+  }
+
   // `node --prof-process`
   if (getOptionValue('--prof-process')) {
     NativeModule.require('internal/v8_prof_processor');