tools: tests: add tests for idle-timeout and debounce period.

tools: tests: add tests for idle-timeout and debounce period.

There are no tests for the --debounce-period for gpiomon, or the new
idle-timeout option for gpiomon and gpionotify, so add some.

In both cases the focus of the test is not the period itself, which is
problematic to test reliably, but that the options are supported and
have the otherwise anticipated effects.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>