tests: add enable_debounce_then_edge_detection

tests: add enable_debounce_then_edge_detection

A bug was recently discovered in the kernel that can result in the edge
event fifo not being correctly initialised and stack contents being
returned in edge events. The trigger for the bug is requesting a line with
debounce, but not edge detection, and then reconfiguring the line to
enable edge detection.

Add a test case that triggers the bug.  This will fail on kernels that
do not contain the fix for the bug.  The test is located in a new test
file, tests-kernel-uapi.c, intended to contain tests specifically
testing some aspect of the kernel uAPI, not libgpiod itself.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20240513160031.309139-1-warthog618@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>