Move the test template to //testing/test.gni (part 2)

This CL move the test target from build/config/BUILDCONFIG.gn to testing/test.gni

It also update the test template to automatically build an apk on Android.

R=cjhopman@chromium.org,brettw@chromium.org

Review URL: https://codereview.chromium.org/824263004

Cr-Commit-Position: refs/heads/master@{#312396}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 746cf75..c3d77177b 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//testing/test.gni")
+
 component("cc") {
   sources = [
     "animation/animation.cc",