lib/oeqa: targetcontrol.py: add abstraction for running tests on different targets

lib/oeqa: targetcontrol.py: add abstraction for running tests on different targets

Add a new module which abstracts the target object used by testimage.bbclass

The purpose of this module is to move the deployment of a target from testimage.bbclass,
basically abstracting different implementations of how we setup a target and how it runs commands.
It allows to select one implementation or another by setting TEST_TARGET (currently to: "qemu" and "simpleremote").

QemuTarget is used to start a qemu instance (as it's currently done in testimage.bbclass)
SimpleRemoteTarget is meant for a remote machine (by setting TEST_TARGET_IP) that's already up and running
with network and ssh.
Simply put, it opens the door for running the tests on different types of targets by adding new classes
(maybe qemu-nfsroot or remote-special etc.). One could also override BaseTarget which currently uses
the existing SSHControl module and add a serial implementation.

[ YOCTO #5554 ]

(From OE-Core rev: c1bfd4017f6f6502a68ceb3edf7d2027d02a309d)

Signed-off-by: Stefan Stanacar <stefanx.stanacar@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>