[js_repl] paths for node module resolution can be specified for js_repl (#11944)

# External (non-OpenAI) Pull Request Requirements

In `js_repl` mode, module resolution currently starts from
`js_repl_kernel.js`, which is written to a per-kernel temp dir. This
effectively means that bare imports will not resolve.

This PR adds a new config option, `js_repl_node_module_dirs`, which is a
list of dirs that are used (in order) to resolve a bare import. If none
of those work, the current working directory of the thread is used.

For example:
```toml
js_repl_node_module_dirs = [
    "/path/to/node_modules/",
    "/other/path/to/node_modules/",
]
```

codex-rs/core/config.schema.json

@@ -331,6 +331,13 @@
         "include_apply_patch_tool": {
           "type": "boolean"
         },
+        "js_repl_node_module_dirs": {
+          "description": "Ordered list of directories to search for Node modules in `js_repl`.",
+          "items": {
+            "$ref": "#/definitions/AbsolutePathBuf"
+          },
+          "type": "array"
+        },
         "js_repl_node_path": {
           "$ref": "#/definitions/AbsolutePathBuf"
         },
@@ -1518,6 +1525,13 @@
       "description": "System instructions.",
       "type": "string"
     },
+    "js_repl_node_module_dirs": {
+      "description": "Ordered list of directories to search for Node modules in `js_repl`.",
+      "items": {
+        "$ref": "#/definitions/AbsolutePathBuf"
+      },
+      "type": "array"
+    },
     "js_repl_node_path": {
       "allOf": [
         {