Streaming bugreport content to stdout 1/2

Add a -s option to bugreportz to support streaming data.

Bug: 162910469
Test: adb bugreport --stream > test.txt
Test: adb shell bugreportz -s > test2.txt
Test: atest dumpstate_test
Test: atest bugreportz_test

Change-Id: I33d68bf742c92a7359a925838827a0033ee68658