EAMxx: add AODvis to derivations

[mahf708]

Description

Exposes AODvis in EAMxx to e3sm_diags infrastructure.

• Closes [Feature]: Support AOD diagnostic in EAMxx #981

Checklist

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

If applicable:

• New and existing unit tests pass with my changes (locally and CI/CD build)
• I have added tests that prove my fix is effective or that my feature works
• 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)

[Copilot]

Pull Request Overview

This PR adds support for the AODvis (Aerosol Optical Depth at 550 nm) variable from EAMxx into the e3sm_diags derivations module.

• Introduces a new input mapping for the EAMxx variable name "AerosolOpticalDepth550nm".
• Ensures that both lowercase and uppercase inputs are renamed consistently to "AODVIS" and converted to dimensionless units.

Comments suppressed due to low confidence (1)

e3sm_diags/derivations/derivations.py:852

• Add or update a unit test to verify that the new "AerosolOpticalDepth550nm" input correctly maps to the standard AODVIS derivation and that units conversion is applied as expected.

("AerosolOpticalDepth550nm",): rename,  # EAMxx

[chengzhuzhang]

@mahf708 thanks for the PR! I haven't forgot about this issue, but added a fix to another EAMxx PR, not yet committed.. Let's merge this so folks can start to use with main branch. Tagging @meng630

[mahf708]

No worries, I was just browsing around, and I thought, I could do this quickly and help out with a quick contribution 😸