Add a bugreport mode

ActivityManager sets a system property to encapsulate a bunch of
commandline arguments to dumpstate. Provide an enumerated alternative so
it can be used in the new binder service.

Bug: 117177665
Test: adb shell /data/nativetest64/dumpstate_test/dumpstate_test
Change-Id: I24cdc2e750e3a00e49d7053a05ddae05d6348bc4