[PR]: Remove deprecated features and APIs for next release

[tomvothecoder]

Description

• Closes #626
• Closes #604

Summary of Changes

• Remove horizontal_xesmf() and horizontal_regrid2()
• Remove **kwargs from create_grid() and _deprecated_create_grid()
• Remove add_bounds accepting boolean arg in open_dataset(), open_mfdataset() and _postprocess_dataset()
• Remove CDML/XML support from open_dataset() and open_mfdataset()
• Remove tests for deprecated APIs and features
• Remove lxml dependency from ci.yml and dev.yml

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published in downstream modules

If applicable:

• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass with my changes (locally and CI/CD build)
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have noted that this is a breaking change for a major release (fix or feature that would cause existing functionality to not work as expected)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (a9b6c5d) to head (c5cdab3).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #628 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 15 15 Lines 1588 1521 -67 ========================================= - Hits 1588 1521 -67 ```

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[tomvothecoder]

I did another self-review and the build is passing. I will merge this PR.