feat(node_compat): Added base implementation of FileHandle (#19294)

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## WHY

ref: https://github.com/denoland/deno/issues/19165

Node's fs/promises includes a FileHandle class, but deno does not. The
open function in Node's fs/promises returns a FileHandle, which provides
an IO interface to the file. However, deno's open function returns a
resource id.


### deno 

```js
> const fs = await import("node:fs/promises");
undefined
> const file3 = await fs.open("./README.md");
undefined
> file3
3
> file3.read
undefined
Node:
```

### Node
```js
> const fs = await import("fs/promises");
undefined
>   const file3 = await fs.open("./tests/e2e_unit/testdata/file.txt");
undefined
> file3
FileHandle {
  _events: [Object: null prototype] {},
  _eventsCount: 0,
  _maxListeners: undefined,
  close: [Function: close],
  [Symbol(kCapture)]: false,
  [Symbol(kHandle)]: FileHandle {},
  [Symbol(kFd)]: 24,
  [Symbol(kRefs)]: 1,
  [Symbol(kClosePromise)]: null
}
> file3.read
[Function: read]
```


To be compatible with Node, deno's open function should also return a
FileHandle.

## WHAT

I have implemented the first step in adding a FileHandle.

- Changed the return value of the open function to a FileHandle object
- Implemented the readFile method in FileHandle
- Add test code


## What to do next
This PR is the first step in adding a FileHandle, and there are things
that should be done next.

- Add functionality equivalent to Node's FileHandle to FileHandle
(currently there is only readFile)

---------

Co-authored-by: Matt Mastracci <matthew@mastracci.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/cli/tests/unit_node/_fs/_fs_handle_test.ts b/cli/tests/unit_node/_fs/_fs_handle_test.ts
new file mode 100644
index 000000000..c1e5ef871
--- /dev/null
+++ b/cli/tests/unit_node/_fs/_fs_handle_test.ts
@@ -0,0 +1,20 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+import * as path from "../../../../test_util/std/path/mod.ts";
+import {
+  assert,
+  assertEquals,
+} from "../../../../test_util/std/testing/asserts.ts";
+
+const moduleDir = path.dirname(path.fromFileUrl(import.meta.url));
+const testData = path.resolve(moduleDir, "testdata", "hello.txt");
+
+Deno.test("readFileSuccess", async function () {
+  const fs = await import("node:fs/promises");
+  const fileHandle = await fs.open(testData);
+  const data = await fileHandle.readFile();
+
+  assert(data instanceof Uint8Array);
+  assertEquals(new TextDecoder().decode(data as Uint8Array), "hello world");
+
+  Deno.close(fileHandle.fd);
+});