[Feature] Add check for NNZ in COOToCSR

[Skeleton003]

Description

Add check for the number of non-zero elements (NNZ) during the conversion from COOMatrix to CSRMatrix within the spmat_op_impl_coo.cc file.

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: 57b1572

Build ID: 1

Status: ❌ CI test failed in Stage [Lint Check].

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[Rhett-Ying]

pls add dedicated testcase

[Skeleton003]

pls add dedicated testcase

I'm afraid it's a little bit difficult because we need to construct a COO with more than 2B NNZ for a testcase.

[dgl-bot]

Commit ID: 73dc413

Build ID: 2

Status: ✅ CI test succeeded.

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[dgl-bot]

Commit ID: 716acae329f74e95ba2294d36bcb8e123fde0c3c

Build ID: 3

Status: ⚪️ CI test cancelled due to overrun.

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[dgl-bot]

Commit ID: afaa2abccb45010ec2f166a87b06f773ee06c1c0

Build ID: 4

Status: ❌ CI test failed in Stage [Distributed Torch CPU Unit test].

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[dgl-bot]

Commit ID: 86f8846

Build ID: 5

Status: ⚪️ CI test cancelled due to overrun.

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[dgl-bot]

Commit ID: 86f8846

Build ID: 6

Status: ✅ CI test succeeded.

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[dgl-bot]

Commit ID: e3b1fad64c3d4151268fb6eeddfe69fd2866619d

Build ID: 7

Status: ❌ CI test failed in Stage [Distributed Torch CPU Unit test].

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[Rhett-Ying]

The CI failed due to glitch in distributed testcases. It's ok to ignore such failures.

[dgl-bot]

Commit ID: 382eda5747196694157684f9d178632748c7527c

Build ID: 8

Status: ✅ CI test succeeded.

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Full logs path: link