Improve WMP dumpsys readability.

It's hard enough to read bugreports without having to decipher all of
the various IntDef's littered around; let's go ahead and just translate
them to something readable.

Bug: 65563703
Test: adb shell dumpsys window policy
Change-Id: Iea6cd309eb3411a65e54217fef814a66107a8e31