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 78e0963e4bce9cc9f0bbf0b686004ba15b1e3929)
(cherry picked from commit 218e1ff75998052c7bb30b483c15e75a853283a8)
9 files changed