Add run order for jobs when using a decorator to schedule a job.

This would be a nice add but I am adding my code here incase someone else wants a solution.

Add the ability to set the order of job set to run at the same time when using a decorator to schedule a job.
I have solved this for myself using the below code.

### Decorator
```python
def func_order(order: int = 0):
def decorator(f):
f.order = order
return f
return decorator
```

### Jobs
```python
@func_order(2)
@repeat(every(1).minutes)
def job1():
print('do job1')

@func_order(1)
@repeat(every(2).minutes)
def job2():
print('do job2')

@repeat(every(2).minutes)
def job3():
# order not set so will be last.
print('do job3')
```

### Main
```python
from schedule import default_scheduler, idle_seconds, jobs

if __name__ == '__main__':
while True:
idle_sec = idle_seconds()
if idle_sec is None:
# No More Jobs.
break
elif idle_sec > 0:
# This is to catch all functions that are close to the same time.
idle_sec += 1
time.sleep(idle_sec)

runnable_jobs = list(filter(lambda job: job.should_run, jobs))
if len(runnable_jobs) == 0:
continue

ordered_jobs = sorted(runnable_jobs, key=lambda job: job.job_func.func.order if hasattr(job.job_func.func, 'order') else 100000)
for job in ordered_jobs:
default_scheduler._run_job(job)
```