bootconfig/tracing/ktest: Add ktest examples of testing bootconfig

bootconfig is a new feature that appends scripts onto the initrd, and the
kernel executes the scripts as an extended kernel command line.

Need to add tests to test that the happened. To test the bootconfig
properly, the initrd needs to be updated and the kernel rebooted. ktest is
the perfect solution to perform these tests.

Add a example bootconfig.conf in the tools/testing/ktest/examples/include
and example bootconfig scripts in tools/testing/ktest/examples/bootconfig
and also include verifier scripts that ktest will install on the target
and run to make sure that the bootconfig options in the scripts took place
after the target rebooted with the new initrd update.

Link: https://lkml.kernel.org/r/20210618112647.6a81dec5@oasis.local.home

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>