kunit: tool: Parse skipped tests from kselftest.h

Skipped tests reported by kselftest.h use a different format than KTAP,
there is no explicit test name. Normally the test name is part of the
free-form string after the SKIP keyword:

	ok 3 # SKIP test: some reason

Extend the parser to handle those correctly. Use the free-form string as
test name instead.

Link: https://lore.kernel.org/r/20250813-kunit-kselftesth-skip-v1-1-57ae3de4f109@linutronix.de


Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>