[feature request] job level scheduling and orchestration

[SimonCqk]

What would you like to be added:

1. a job-level queuing and orchestration module that admit job to be scheduled by some strategies.
2. refactor skeleton codes to make control flow cleaner.

Why is this needed:

as for now, kubedl is capable to manage lifecycle of job workloads, manipulate pods from job started to succeeded or failed, however, in production users usually requests jobs(=resources) more resources than cluster capacity, therefore, job s have to wait in queue before getting chance to be schedule, for the reason that we propose a new module&policy to coordinate job schedule orders.

• assign job priority via schedulePolicy
• coordinator job schedule orders by job-coordinator.

[jian-he]

@SimonCqk could you clarify on this ?

[SimonCqk]

@jian-he I have updated the description