Added system property (dumpstate.unroot) to run dumpstate as shell.

This is useful to test how it would behave on devices with user builds.

Bug: 117980186
Test: adb shell setprop dumpstate.unroot true && \
      adb shell cmd activity bug-report --progress

Change-Id: If9094bbe0c29e8180f1b35d2b4ac95343a1bd0eb