Add support for HTTP handlers that are in self-contained apps. Also add an example app.

examples/http_handler/BUILD.gn

Index: examples/http_handler/BUILD.gn
diff --git a/sky/tools/debugger/prompt/BUILD.gn b/examples/http_handler/BUILD.gn
similarity index 61%
copy from sky/tools/debugger/prompt/BUILD.gn
copy to examples/http_handler/BUILD.gn
index ff6f82bd47f3f4911e6584e615b92ed45e98287d..ef52c75659e807973fe2425e67106ee6d8a8785b 100644
--- a/sky/tools/debugger/prompt/BUILD.gn
+++ b/examples/http_handler/BUILD.gn
@@ -2,20 +2,17 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-shared_library("prompt") {
-  output_name = "sky_debugger_prompt"
-
+shared_library("http_handler") {
   sources = [
-    "prompt.cc",
+    "http_handler.cc"
   ]
 
   deps = [
-    "//base",
     "//mojo/application",
     "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/bindings",
-    "//mojo/public/cpp/utility",
-    "//sky/tools/debugger:bindings",
-    "//sky/viewer:bindings",
+    "//services/http_server",
+    "//services/http_server/public",
+    "//services/http_server/public:util",
   ]
 }