Update FatesPFTIndexSwapper.py to work with landuse dimension

[JessicaNeedham]

The new land use class dimension in the fates parameter file means that FatesPFTIndexSwapper.py needs to be updated.

Collaborators:

Expectation of Answer Changes:

These are minor changes only to FatesPFTIndexSwapper.py and will not affect FATES runs.

Checklist

If this is your first time contributing, please read the CONTRIBUTING document.

All checklist items must be checked to enable merging this pull request:

Contributor

• The in-code documentation has been updated with descriptive comments
• The documentation has been assessed to determine if updates are necessary

Integrator

• FATES PASS/FAIL regression tests were run
• Evaluation of test results for answer changes was performed and results provided

Documentation

• Technical Note update:
• User's Guide update:

Test Results:

CTSM (or) E3SM (specify which) test hash-tag:

CTSM (or) E3SM (specify which) baseline hash-tag:

FATES baseline hash-tag:

Test Output:

[glemieux]

I conducted a quick check with @JessicaNeedham help and the tools appears to work as expected.