[Enhancement]: Handle descending bounds with horizontal regridding

[tomvothecoder]

Is your feature request related to a problem?

We found that descending bounds ("out of order" bounds) can throw off results with xESMF's horizontal regridding. CDAT seemed to rectify bounds implicitly before performing the regridding.

Example with e3sm_diags and Hadley SST dataset:

v2.12.1 CDAT RMSE (weighted, bilinear): 1.476555924046852
v2.12.1 CDAT RMSE (weighted, conservative): 1.4764821102067773
v3.0.0 Xarray RMSE (weighted, bilinear): 1.4763235405423747
v3.0.0 Xarray RMSE (weighted normalized, conservative_normed): 1.7713504288524176
v3.0.0 Xarray RMSE (weighted normalized, conservative_normed, bnds fix): 1.4764820110242953

Related issues

• #338
• https://github.com/E3SM-Project/e3sm_diags/issues/945
• https://github.com/E3SM-Project/e3sm_diags/pull/940#issuecomment-2711274827

Describe the solution you'd like

1. Check order of bounds
2. If they are descending/out of order:

• Raise warning
• Rectify bounds by making them ascending order

3. Perform regrid

Describe alternatives you've considered

No response

Additional context

No response