[Traffic Annotations] check_network_annotations when XML changes

Previously, if a CL only modified annotations.xml, CQ wouldn't run
check_network_annotations because the file doesn't appear in the
dependency tree for shipped_binaries.

This CL adds annotations.xml to shipped_binaries, solving that issue.

TESTED=Created a dependent CL that updates only annotations.xml and
       checked that it fails on CQ:
   https://chromium-review.googlesource.com/c/chromium/src/+/1758433

Change-Id: Ib33099df057f1cef882c46858862ea5fca5b91e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1757297Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688482}

BUILD.gn

@@ -806,6 +806,7 @@ if ((is_linux || is_win) && enable_remoting && !use_ozone) {
     deps = [
       "//chrome:chrome",
       "//remoting/host:host",
+      "//tools/traffic_annotation/summary:annotations_xml",
     ]
   }
 }

tools/traffic_annotation/summary/BUILD.gn

+# Copyright (c) 2019 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.
+
+copy("annotations_xml") {
+  sources = [
+    "annotations.xml",
+  ]
+  outputs = [
+    "$target_out_dir/annotations.xml",
+  ]
+}