lib: restructure cjs and esm loaders

Create `lib/internal/modules` and restructure the module loaders
to make the purpose of those files clearer.

Also make it clear in the code that the object exported by
`lib/internal/modules/cjs/loader.js` is `CJSModule` instead of the
ambiguous `Module`.

Before:

```
lib
├── ...
├── internal
│       ├── loaders
│       │     ├── CreateDynamicModule.js
│       │     ├── DefaultResolve.js
│       │     ├── Loader.js
│       │     ├── ModuleJob.js
│       │     ├── ModuleMap.js
│       │     └── Translators.js
│       └── module.js
└── module.js
```

After:

```
lib
├── ...
├── internal
│       ├── ...
│       └── modules
│              ├── cjs
│              │     ├── helpers.js
│              │     └── loader.js
│              └── esm
│                    ├── CreateDynamicModule.js
│                    ├── DefaultResolve.js
│                    ├── Loader.js
│                    ├── ModuleJob.js
│                    ├── ModuleMap.js
│                    └── Translators.js
└── module.js # deleted in this commit to work with git file mode
```

PR-URL: https://github.com/nodejs/node/pull/19177
Refs: https://github.com/nodejs/node/pull/19112
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

2 files changed, 12 insertions, 8 deletions

diff --git a/test/fixtures/module-require-depth/one.js b/test/fixtures/module-require-depth/one.js
index 5927908b75..02b451465b 100644
--- a/test/fixtures/module-require-depth/one.js
+++ b/test/fixtures/module-require-depth/one.js
@@ -1,9 +1,11 @@
 // Flags: --expose_internals
 'use strict';
 const assert = require('assert');
-const internalModule = require('internal/module');
+const {
+  requireDepth
+} = require('internal/modules/cjs/helpers');
 
-exports.requireDepth = internalModule.requireDepth;
-assert.strictEqual(internalModule.requireDepth, 1);
+exports.requireDepth = requireDepth;
+assert.strictEqual(requireDepth, 1);
 assert.deepStrictEqual(require('./two'), { requireDepth: 2 });
-assert.strictEqual(internalModule.requireDepth, 1);
+assert.strictEqual(requireDepth, 1);
diff --git a/test/fixtures/module-require-depth/two.js b/test/fixtures/module-require-depth/two.js
index aea49947d1..5c94c4c89a 100644
--- a/test/fixtures/module-require-depth/two.js
+++ b/test/fixtures/module-require-depth/two.js
@@ -1,9 +1,11 @@
 // Flags: --expose_internals
 'use strict';
 const assert = require('assert');
-const internalModule = require('internal/module');
+const {
+  requireDepth
+} = require('internal/modules/cjs/helpers');
 
-exports.requireDepth = internalModule.requireDepth;
-assert.strictEqual(internalModule.requireDepth, 2);
+exports.requireDepth = requireDepth;
+assert.strictEqual(requireDepth, 2);
 assert.deepStrictEqual(require('./one'), { requireDepth: 1 });
-assert.strictEqual(internalModule.requireDepth, 2);
+assert.strictEqual(requireDepth, 2);