reorg: move JS ops implementations to cli/js/ops/, part 3 (#4302)

Following JS ops were moved to separate files in cli/js/ops directory:
- net
- tls
- fs

cli/js/ops/fs/link.ts

@@ -0,0 +1,20 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { sendSync, sendAsync } from "../dispatch_json.ts";
+
+/** Creates `newname` as a hard link to `oldname`.
+ *
+ *       Deno.linkSync("old/name", "new/name");
+ *
+ * Requires `allow-read` and `allow-write` permissions. */
+export function linkSync(oldname: string, newname: string): void {
+  sendSync("op_link", { oldname, newname });
+}
+
+/** Creates `newname` as a hard link to `oldname`.
+ *
+ *       await Deno.link("old/name", "new/name");
+ *
+ * Requires `allow-read` and `allow-write` permissions. */
+export async function link(oldname: string, newname: string): Promise<void> {
+  await sendAsync("op_link", { oldname, newname });
+}