fix calculations of podgroup min resource

[lowang-bh]

commit 1: refact jobinfo's calculation to a function.
commit 2: fix cal podgroup min resource and add testcase. relative design docs: docs about job's min resource #2945
commit 3: when jobMinAvailable < totalTask's, keep the origin logic of calculate podgorup minResource: sum up first jobMinAvailable

Fix #2921 also.

[lowang-bh]

/assign @wangyang0616 @hwdef @Yikun @Thor-wl @william-wang

Hi, all guys, would you please have a look at this pr and let us discuss the remaining case (jobMinAvailable < sumup(taskMinAvailable)), eg, jobMinAvailable=2, totalTaskMinAvailable=3, we should sum up at most 2 or 3 member's resource as the job's min resource?

I have an idea is to validate the jobMinAvailable and taskTotalMinAvailable. Now there is only validations about jobMinAvailable vs totalReplicas.

But there is also another thing need to be noted: task is allocated from high priorith to low priority in allocate action, utill all jobMinAvaiable tasks allocated, then it is ready to commit.
Consider this scenario: queue with capacity 2C, job with jobMinAvailable=2 has two master, each requst 1c, and taskMinAvailable =1, two workers, each requst 0.5c and taskMinAvailable=2. The idea allocation process is 1master and then 2 workers. But current allocation process is 2master (high priority) allocated first and used up queue capacity and then job can not be ready. (maybe we need to enqueue task which is min available to tasks queue)

volcano/pkg/scheduler/api/job_info.go

Lines 758 to 763 in 8d8b691

	for taskID, minNum := range ji.TaskMinAvailable {
	if occupiedMap[taskID] < minNum {
	klog.V(4).Infof("Job %s/%s Task %s occupied %v less than task min avaliable", ji.Namespace, ji.Name, taskID, occupiedMap[taskID])
	return false
	}
	}

[lowang-bh]

trigger CI

[lowang-bh]

/assign @k82cn @kevin-wangzefeng

[lowang-bh]

/assign @Monokaix

[Monokaix]

Hi，please resolve code conflict.

[Monokaix]

/lgtm

[william-wang]

/approve

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