[REVIEW] Apply modifications to account for RAFT changes

[viclafargue]

This PR apply modifications to the cuML codebase to account for changes in RAFT and RMM :

• [REVIEW] Replace RAFT device::buffer adapter with RMM device_uvector raft#283
• [REVIEW] Remove references to RAFT device::allocator adapter raft#285
• [REVIEW] Miscellaneous tech debts/cleanups raft#286
• [REVIEW] Execution policy class rmm#816

[ajschmidt8]

Removing ops-codeowners from the required reviews since it doesn't seem there are any file changes that we're responsible for. Feel free to add us back if necessary.

Also, please consider using Draft pull requests instead of the WIP tag for PRs that are still in progress. Draft pull requests have the advantage of not notifying codeowners until the PR is marked Ready for Review.

For reference here's the GitHub docs on draft pull requests: https://docs.github.com/en/github/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests#draft-pull-requests

[dantegd]

rerun tests

[dantegd]

rerun tests

[viclafargue]

rerun tests

[dantegd]

@viclafargue I think the only issue remaining to pass CI is correcting C++ docstrings!!!

Generating docs for file /workspace/cpp/src_prims/metrics/silhouette_score.cuh/workspace/cpp/include/cuml/tsa/arima_common.h:67: error: 
argument 'alloc' of command @param is not found in the argument list of ML::ARIMAParams< DataT >::allocate(const 
ARIMAOrder &order, int batch_size, cudaStream_t stream, bool tr=false) (warning treated as error, aborting now)

...

[dantegd]

rerun tests

[dantegd]

rerun tests

[codecov-commenter]

Codecov Report

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@@               Coverage Diff               @@
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  Coverage                ?   85.96%           
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  Files                   ?      232           
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  Hits                    ?    15906           
  Misses                  ?     2596           
  Partials                ?        0           

Flag	Coverage Δ
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non-dask	78.57% <0.00%> (?)

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[dantegd]

@gpucibot merge