Adding next kernel alarm time to alarm dumpsys

Adding a native method to query timerfd_gettime. This is helpful in
debugging because it will tell for certain whether the kernel timer was
armed or not and whether it matches the expectation of higher level code
in the service.

Test: adb shell dumpsys alarm

Bug: 78560047
Change-Id: If08ebf69b0bde7e8f504d81b98e3f41ecf7f2dc2