reorg: move JS ops implementations to cli/js/ops/, part 1 (#4264)

Following JS ops were moved to separate files in cli/js/ops directory:
- compiler
- dispatch_json
- dispatch_minimal
- errors
- fetch
- fs_events
- os
- random
- repl
- resources
- runtime_compiler
- runtime
- tty

cli/js/net.ts

@@ -1,7 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 import { EOF, Reader, Writer, Closer } from "./io.ts";
-import { read, write, close } from "./files.ts";
-import { sendSync, sendAsync } from "./dispatch_json.ts";
+import { read, write } from "./files.ts";
+import { close } from "./ops/resources.ts";
+import { sendSync, sendAsync } from "./ops/dispatch_json.ts";
 
 export type Transport = "tcp" | "udp";
 // TODO support other types: