Build MojoRunnerApptests.apk for mojo_apptests target on Android.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 882690a258e47a22227b8defcd6095e0e281cc2b..87597e57767aa5cbec99ded0497ecee970caac13 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -615,10 +615,16 @@ group("mojo_apptests") {
       "//components/resource_provider:resource_provider_unittests",
       "//mash/wm:tests",
       "//media/mojo/services:tests",
+      "//mojo/services/network:apptests",
+      "//mojo/shell:apptests",
       "//sql/mojo:apptests",
       "//ui/views/mus:tests",
     ]
   }
+
+  if (is_android) {
+    deps += [ "//mojo/shell/standalone:mojo_shell_standalone_apptests_apk" ]
+  }
 }
 
 group("gn_only") {