[GraphBolt][io_uring] Launch parallel_for when queues are available.

[mfbalin]

Description

We can rely on our existing libcudacxx dependency on the CPU backend for its library facilities. Does not require CUDA or GPUs at all.

Checklist

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [$CATEGORY] (such as [NN], [Model], [Doc], [Feature]])
• I've leverage the tools to beautify the python and c++ code.
• The PR is complete and small, read the Google eng practice (CL equals to PR) to understand more about small PR. In DGL, we consider PRs with less than 200 lines of core code change are small (example, test and documentation could be exempted).
• All changes have test coverage
• Code is well-documented
• To the best of my knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change
• Related issue is referred in this PR
• If the PR is for a new model/paper, I've updated the example index here.

Changes

[dgl-bot]

To trigger regression tests:

• @dgl-bot run [instance-type] [which tests] [compare-with-branch];
  For example: @dgl-bot run g4dn.4xlarge all dmlc/master or @dgl-bot run c5.9xlarge kernel,api dmlc/master

[dgl-bot]

Commit ID: 686b7b5

Build ID: 1

Status: ❌ CI test failed in Stage [CPU Build].

Report path: link

Full logs path: link

[dgl-bot]

Commit ID: 8c0a3ebc6bd856bcf43d637ee1f43ad0b69077f8

Build ID: 2

Status: ❌ CI test failed in Stage [CPU Build].

Report path: link

Full logs path: link

[dgl-bot]

Commit ID: 89892968f5ee61f6b269f9a138948c08165aef68

Build ID: 3

Status: ❌ CI test failed in Stage [CPU Build].

Report path: link

Full logs path: link

[dgl-bot]

Commit ID: 0bf3179289c967e12cf2c6ffb43290fd66b80d91

Build ID: 4

Status: ✅ CI test succeeded.

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Full logs path: link

[dgl-bot]

Commit ID: 5d21fa53af8fa59f1e27d581eecb36bf2ed0d0b2

Build ID: 5

Status: ⚪️ CI test cancelled due to overrun.

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Full logs path: link

[dgl-bot]

Commit ID: 8456fb3c2664a95d788bd54046cf5244c4be737f

Build ID: 6

Status: ✅ CI test succeeded.

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Full logs path: link