Move ActionManager to its own file

Bug: 36970783
Test: build
Change-Id: I08fa39052236b462249f79de1d02bf02bdbf4c84
diff --git a/init/Android.bp b/init/Android.bp
index e218d2a..1f2ad2e 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -93,6 +93,7 @@
     defaults: ["init_defaults"],
     srcs: [
         "action.cpp",
+        "action_manager.cpp",
         "action_parser.cpp",
         "bootchart.cpp",
         "builtins.cpp",