Make skydb just a ctl-style helper (e.g. apachectl)

sky/tools/debugger/prompt/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//mojo/public/mojo_application.gni")
 
 mojo_native_application("prompt") {
   output_name = "sky_debugger_prompt"
 
   sources = [
     "prompt.cc",
   ]
 
   deps = [
     "//base",
     "//mojo/application",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/utility",
+    "//net",
+    "//net:http_server",
     "//services/tracing:bindings",
     "//sky/tools/debugger:bindings",
     "//sky/viewer:bindings",
   ]
 }