…ss the job is set to run. If the job contains _seconds, eg. it's using seconds, minutes, hours, etc. then only set the _next_fire_time if the job actually runs. Adding more tests to test simple scenarios when seconds, minutes, hours and days to ensure we get multiple scheduled job runs when they're expected to run.

…t_fire_time (if we're using time elements) if the job successfully runs.

…a contains '_seconds' and we're running in standalone, always set the _next_fire_time. If the job was skipped, set the _next_fire_time, if there are _seconds, same if the run successfully ran.

…_next_run_time is correct. Adding a run_seconds_skip to ensure skipping is working with time elements and the _next_fire_time is populated.