Sparse arrays

[Yuriyzabegaev]

Proposed changes

This covers #1319. Made by @IngridKJ and me.

Types of changes

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• Minor change (e.g., dependency bumps, broken links).
• Bugfix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Testing (contribution related to testing of existing or new functionality).
• Documentation (contribution related to adding, improving, or fixing documentation).
• Maintenance (e.g., improve logic and performance, remove obsolete code).
• Other:

Checklist

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• The documentation is up-to-date.
• Static typing is included in the update.
• This PR does not duplicate existing functionality.
• The update is covered by the test suite (including tests added in the PR).
• If new skipped tests have been introduced in this PR, pytest was run with the --run-skipped flag.

[IvarStefansson]

Before we proceed, could you please verify (locally) that the tests pass if you change to sparray somewhere in the models?

[Yuriyzabegaev]

Before we proceed, could you please verify (locally) that the tests pass if you change to sparray somewhere in the models?

I confirm that all tests pass when we change coo_matrix to coo_array in cell_projections and face_projections in grid_operators.py.

[IvarStefansson]

Thanks to both of you for quick and good work!