Add oblique mercator to create_bounds and other improvements to the regridding function

[RondeauG]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes #xyz
• (If applicable) Documentation has been added / updated (for bug fixes / features).
• (If applicable) Tests have been added.
• This PR does not seem to break the templates.
• CHANGELOG.rst has been updated (with summary of main changes).
  • Link to issue (:issue:number) and pull request (:pull:number) has been added.

What kind of change does this PR introduce?

• Renames create_bounds_rotated_pole to create_bounds_gridmapping and adds support for oblique_mercator.
• Changes to regrid_dataset:
  • weights_location is now optional.
  • Reinforced the automatic naming of the weights file. When attributes are unknown, a random string is now generated instead of a static one. Moreover, it now relies on a cat:id and cat:domain for both the incoming dataset and the grid.
  • Now correctly skips the lon_bounds and lat_bounds variables if the grid was generated using xesmf.util.cf_grid_2d
• create_mask has been completely refactored to use real arguments instead of a dictionary.

Does this PR introduce a breaking change?

• The old function name is deprecated and will be dropped in a later version.
• weights_location in regrid_dataset is now optional, and thus had to be moved to explicit arguments rather than positional.

Other information:

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[aulemahal]

This looks good!