Deprecate pygmt.io.load_dataarray, use xarray.load_dataarray instead

[weiji14]

Description of proposed changes

Deprecate usage of pygmt.io.load_dataarray for loading NetCDF and other grids, use xr.load_dataarray(..., engine="gmt") instead.

TODO:

• Add FutureWarning
• Update load_dataarray to xr.load_dataarray(..., engine="gmt", raster_kind="grid") internally
• Move benchmark on test_io_load_dataarray to somewhere else
• etc

Cherry-picked from #3919

Preview:

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.

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[seisman]

Perhaps we should also replace xr.open_dataarray with xr.load_dataarray in the tests?

[weiji14]

Perhaps we should also replace xr.open_dataarray with xr.load_dataarray in the tests?

I see you're doing some of that in #3643 already. Do you want to do it there, or in this PR?

[codspeed-hq]

CodSpeed Performance Report

Merging #3922 will degrade performances by 85.18%

_{Comparing deprecate/load_dataarray (898f349) with main (f389e05)}

Summary

❌ 2 regressions
✅ 102 untouched benchmarks
🆕 1 new benchmarks
⁉️ 1 dropped benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	test_put_matrix_grid	69 ms	465.9 ms	-85.18%
❌	test_earth_relief_holes	39.2 ms	66 ms	-40.6%
⁉️	test_io_load_dataarray	23.9 ms	N/A	N/A
🆕	test_xarray_backend_load_dataarray	N/A	64.7 ms	N/A

[seisman]

Perhaps we should also replace xr.open_dataarray with xr.load_dataarray in the tests?

I see you're doing some of that in #3643 already. Do you want to do it there, or in this PR?

Please do it in this PR.