Update `get_bounds()` to support mappable non-CF axes using `"bounds"` attr

[tomvothecoder]

Description

• Closes #707

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
• [ ] 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 (e3dda64) to head (338d71f). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #708 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 15 15 Lines 1546 1555 +9 ========================================= + Hits 1546 1555 +9 ```

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