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/truncate.ts

@@ -1,33 +0,0 @@
-// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
-
-function coerceLen(len?: number): number {
-  if (!len) {
-    return 0;
-  }
-
-  if (len < 0) {
-    return 0;
-  }
-
-  return len;
-}
-
-/** Synchronously truncates or extends the specified file, to reach the
- * specified `len`.
- *
- *       Deno.truncateSync("hello.txt", 10);
- *
- * Requires `allow-write` permission. */
-export function truncateSync(path: string, len?: number): void {
-  sendSync("op_truncate", { path, len: coerceLen(len) });
-}
-
-/** Truncates or extends the specified file, to reach the specified `len`.
- *
- *       await Deno.truncate("hello.txt", 10);
- *
- * Requires `allow-write` permission. */
-export async function truncate(path: string, len?: number): Promise<void> {
-  await sendAsync("op_truncate", { path, len: coerceLen(len) });
-}