chore: move cli/tests/ -> tests/ (#22369)

This looks like a massive PR, but it's only a move from cli/tests ->
tests, and updates of relative paths for files.

This is the first step towards aggregate all of the integration test
files under tests/, which will lead to a set of integration tests that
can run without the CLI binary being built.

While we could leave these tests under `cli`, it would require us to
keep a more complex directory structure for the various test runners. In
addition, we have a lot of complexity to ignore various test files in
the `cli` project itself (cargo publish exclusion rules, autotests =
false, etc).

And finally, the `tests/` folder will eventually house the `test_ffi`,
`test_napi` and other testing code, reducing the size of the root repo
directory.

For easier review, the extremely large and noisy "move" is in the first
commit (with no changes -- just a move), while the remainder of the
changes to actual files is in the second commit.

tests/unit_node/_fs/_fs_readdir_test.ts

@@ -0,0 +1,96 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+import {
+  assertEquals,
+  assertNotEquals,
+  fail,
+} from "@test_util/std/assert/mod.ts";
+import { assertCallbackErrorUncaught } from "../_test_utils.ts";
+import { readdir, readdirSync } from "node:fs";
+import { join } from "@test_util/std/path/mod.ts";
+
+Deno.test({
+  name: "ASYNC: reading empty directory",
+  async fn() {
+    const dir = Deno.makeTempDirSync();
+    await new Promise<string[]>((resolve, reject) => {
+      readdir(dir, (err, files) => {
+        if (err) reject(err);
+        resolve(files);
+      });
+    })
+      .then((files) => assertEquals(files, []), () => fail())
+      .finally(() => Deno.removeSync(dir));
+  },
+});
+
+function assertEqualsArrayAnyOrder<T>(actual: T[], expected: T[]) {
+  assertEquals(actual.length, expected.length);
+  for (const item of expected) {
+    const index = actual.indexOf(item);
+    assertNotEquals(index, -1);
+    expected = expected.splice(index, 1);
+  }
+}
+
+Deno.test({
+  name: "ASYNC: reading non-empty directory",
+  async fn() {
+    const dir = Deno.makeTempDirSync();
+    Deno.writeTextFileSync(join(dir, "file1.txt"), "hi");
+    Deno.writeTextFileSync(join(dir, "file2.txt"), "hi");
+    Deno.mkdirSync(join(dir, "some_dir"));
+    await new Promise<string[]>((resolve, reject) => {
+      readdir(dir, (err, files) => {
+        if (err) reject(err);
+        resolve(files);
+      });
+    })
+      .then(
+        (files) =>
+          assertEqualsArrayAnyOrder(
+            files,
+            ["file1.txt", "some_dir", "file2.txt"],
+          ),
+        () => fail(),
+      )
+      .finally(() => Deno.removeSync(dir, { recursive: true }));
+  },
+});
+
+Deno.test({
+  name: "SYNC: reading empty the directory",
+  fn() {
+    const dir = Deno.makeTempDirSync();
+    assertEquals(readdirSync(dir), []);
+  },
+});
+
+Deno.test({
+  name: "SYNC: reading non-empty directory",
+  fn() {
+    const dir = Deno.makeTempDirSync();
+    Deno.writeTextFileSync(join(dir, "file1.txt"), "hi");
+    Deno.writeTextFileSync(join(dir, "file2.txt"), "hi");
+    Deno.mkdirSync(join(dir, "some_dir"));
+    assertEqualsArrayAnyOrder(
+      readdirSync(dir),
+      ["file1.txt", "some_dir", "file2.txt"],
+    );
+  },
+});
+
+Deno.test("[std/node/fs] readdir callback isn't called twice if error is thrown", async () => {
+  // The correct behaviour is not to catch any errors thrown,
+  // but that means there'll be an uncaught error and the test will fail.
+  // So the only way to test this is to spawn a subprocess, and succeed if it has a non-zero exit code.
+  // (assertRejects won't work because there's no way to catch the error.)
+  const tempDir = await Deno.makeTempDir();
+  const importUrl = new URL("node:fs", import.meta.url);
+  await assertCallbackErrorUncaught({
+    prelude: `import { readdir } from ${JSON.stringify(importUrl)}`,
+    invocation: `readdir(${JSON.stringify(tempDir)}, `,
+    async cleanup() {
+      await Deno.remove(tempDir);
+    },
+  });
+});