convert BUILD_CTS_SUPPORT_PACKAGE in mk files

1. Modified the logic of the androidmk tool, to convert the BUILD_CTS_SUPPORT_PACKAGE
field to the android_test_helper_app module type rather than android_test;
2. Updated the unit tests as well.

Bug: 191907322
Test: m androidmk
Test: TreeHugger
Change-Id: Iabff299f6d043521481ef1af457c708353559823

androidmk/androidmk/androidmk_test.go

@@ -794,7 +794,7 @@ LOCAL_MODULE_PATH := $(TARGET_OUT_DATA_APPS)
 include $(BUILD_CTS_SUPPORT_PACKAGE)
 `,
 		expected: `
-android_test {
+android_test_helper_app {
     name: "FooTest",
     defaults: ["cts_support_defaults"],
     test_suites: ["cts"],