Add a module containing kunit test cases for GPIO core. The idea is to use it to test functionalities that can't easily be tested from user-space with kernel selftests or GPIO character device test suites provided by the libgpiod package. For now add test cases that verify software node based lookup and ensure that a GPIO provider unbinding with active consumers does not cause a crash. Reviewed-by: David Gow <david@davidgow.net> Reviewed-by: Linus Walleij <linusw@kernel.org> Link: https://patch.msgid.link/20260522-gpiolib-kunit-v3-3-b15fe6987430@oss.qualcomm.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>