Make gridmapping creation faster for 2d coordinates

[konstntokas]

• Improved performance when creating GridMapping from 2D coordinates.
  Parameter estimation now uses only corner points instead of the full set of
  coordinates, significantly reducing runtime for large datasets.

xcube-resampling v0.2.3 (previous release)

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xcube-resampling v0.2.4.dev0 (this PR)

Includes the performance improvements introduced in this PR.

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Note that the previous release is identical with the implementation in xcube.
new_version.ipynb
old_version.ipynb
xcube_version.ipynb

Note as a test dataset, a Senintle-3 OLCI Level-1 EOPF Zarr sample is taken from https://stac.browser.user.eopf.eodc.eu/collections/sentinel-3-olci-l1-efr

Checklist:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/
• Changes documented in CHANGES.md
• CI checks pass
• Test coverage remains or increases (target 100%)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.85%. Comparing base (dde72ce) to head (4930532).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #19      +/-   ##
==========================================
+ Coverage   98.81%   98.85%   +0.04%     
==========================================
  Files          22       22              
  Lines        2189     2182       -7     
==========================================
- Hits         2163     2157       -6     
+ Misses         26       25       -1     

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[b-yogesh]

LGTM, but please consider answering my questions. They are just for me to understand this algorithm better. We can a short call as well.