KMeans OOP

[md-shafiul-alam]

This PR intends to take KMeans algorithm out of preview namespace. The changes proposed:

• KMeans out of preview
• add sparsity support for KMeans
• reduce number of deselected tests for KMeans

Nuances: KMeans Init does not have GPU support for sparse data. Hence CPU implementation is used using Host policy.

Based on #1634.
Needs to merge uxlfoundation/oneDAL#2815 first.

Fixes # - issue number(s) if exists

• I have reviewed my changes thoroughly before submitting this pull request.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes, if necessary (updated in # - add PR number)
• The unit tests pass successfully.
• I have run it locally and tested the changes extensively.
• I have resolved any merge conflicts that might occur with the base branch.
• Git commit message contains an appropriate signed-off-by string (see CONTRIBUTING.md for details)
• I have added a respective label(s) to PR if I have a permission for that.

[md-shafiul-alam]

/intelci: run

[icfaust]

I know its a draft, but this is a note for my future review: please enable all k_means GPU tests (i.e. remove from deselected_tests) and see what passes. This will be necessary to pull this code out of preview.

[md-shafiul-alam]

/intelci: run

[md-shafiul-alam]

/azp run CI

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[md-shafiul-alam]

/intelci: run

[md-shafiul-alam]

/azp run CI

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[md-shafiul-alam]

/intelci: run

[samir-nasibli]

/intelci: run

[md-shafiul-alam]

/intelci: run

[md-shafiul-alam]

/intelci: run

[md-shafiul-alam]

/intelci: run

[md-shafiul-alam]

The private CI warnings are not related.

[ethanglaser]

Great work on tests!

[ethanglaser]

Great work on this. CI is in good shape and test coverage is nice. Pending resolution of any unresolved comments and manager approval.