DO NOT MERGE: Split bugreport() into its own file and added unit tests.

bugreport() will be soon refactored to track progress, which will
require more comprehensive unit tests.

As such, it's better to move it to its own files, which in turn also
requires moving send_shell_command() and usage() to commandline.h.

Fixes: 30100363
Bug: 30268737

Change-Id: I3cdf114a0b5547293320042ff0749a60886440b0
(cherry picked from commit a9be4f3b16ca3af7bb5ee3c09c0f511d6a0d1a5b)
(cherry picked from commit b9f1b1cf41f3c9e28b630c4e3656aef4f08e85be)
9 files changed