Add main dex Proguard rules for YouTube 12.22

Update the application runner script to handle main dex rules.

R=ager@google.com

Change-Id: Ie6742fa4e59f7030fd5af393cb3f3e73a46a51ce
diff --git a/tools/run_on_app.py b/tools/run_on_app.py
index 9b4cb4d..574830c 100755
--- a/tools/run_on_app.py
+++ b/tools/run_on_app.py
@@ -127,6 +127,9 @@
         args.extend(['--pg-conf', pgconf])
     if options.k:
       args.extend(['--pg-conf', options.k])
+    if 'multidexrules' in values:
+      for rules in values['multidexrules']:
+        args.extend(['--multidex-rules', rules])
 
   if not options.no_libraries and 'libraries' in values:
     for lib in values['libraries']: