Add support for windowed alarms in MPAS timekeeping

This commit adds active windows to recurring alarms. If users do not
provide a start or stop time, they default to the clock start and stop,
so existing behavior is unchanged. New helpers simplify the logic and
are validated indirectly through behavior-level tests, allowing future
refactoring without breaking the suite. A new test fixture and 16-case
suite verify alarm behavior across boundaries, resets, anchors, and
direction changes, documenting the alarm ringing contract and ensuring
safe future development of MPAS timekeeping.

Author: Andy Stokely

src/core_test/mpas_test_core.F

@@ -242,6 +242,18 @@ function test_core_run(domain) result(iErr)!{{{
       end if
       call mpas_log_write('')
 
+      !
+      ! Test functionality of alarms with user-defined active windows
+      !
+      call mpas_log_write('')
+      call mpas_log_write('Testing mpas_window_alarms:')
+      iErr = mpas_window_alarm_tests(domain)
+      if (iErr == 0) then
+         call mpas_log_write('* mpas_window_alarm tests - all tests passed: SUCCESS')
+      else
+         call mpas_log_write('* mpas_window_alarm tests - $i failed tests: FAILURE', intArgs=[iErr])
+      end if
+
       deallocate(threadErrs)
 
    end function test_core_run!}}}