[data] Fix map operator fusion when concurrency is set

[raulchen]

Why are these changes needed?

Current operator fusion rule doesn't consider concurrency.
This PR fixes this issue by only allow fusing 2 operators when they have the same concurrency.
For task->actor, we allow fusion when task's concurrency = actor's upper bound.
Also fixed some type hinting issues regarding compute strategy.

Related issue number

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[Jay-ju]

Can the fuse operator be used as a switch to ignore the choice of GPU/CPU and concurrent settings? As long as the switch is turned on, fusion is performed. This is very useful for the situation of out-of-memory (OOM).

[gvspraveen]

Any reason you are disallowing upstream op being Actor here?

Previous logic seems to permit Actor -> Task as long as compute are compatible/same.

is_task_compute(down_logical_op._compute) and get_compute(
                up_logical_op._compute
            ) != get_compute(down_logical_op._compute)
         return False

[raulchen]

Actor -> Task is already disallowed by this condition above.

[gvspraveen]

for future. if resource requirements are same, should we allow Actor -> Task fuse?

[raulchen]

Can the fuse operator be used as a switch to ignore the choice of GPU/CPU and concurrent settings? As long as the switch is turned on, fusion is performed. This is very useful for the situation of out-of-memory (OOM).

Can you just set the same args to allow fusion?

[Jay-ju]

Can the fuse operator be used as a switch to ignore the choice of GPU/CPU and concurrent settings? As long as the switch is turned on, fusion is performed. This is very useful for the situation of out-of-memory (OOM).

Can you just set the same args to allow fusion?

Is it also possible if one is a CPU and the other is a GPU?