Enable DBH initialization to "full FATES" on coldstarts

[rgknox]

Description:

This enables FATES to use DBH to specify initial conditions for a cold-start run with full fates. This does so by making an equal area assumption of all cohorts. Like with nocomp, it also assumes that plants on the patch fill up a single canopy layer.

Collaborators:

Expectation of Answer Changes:

Description of generative AI usage (as necessary)

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
• Describe use of generative AI (if necessary)

Integrator

• FATES PASS/FAIL regression tests were run
• Evaluation of test results for answer changes was performed and results provided
• FATES-CLM6 Code Freeze: satellite phenology regression tests are b4b

If satellite phenology regressions are not b4b, please hold merge and notify the FATES development team.

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:

[mvdebolskiy]

@rgknox are we going with this option or the #1550 ?

[rgknox]

@mvdebolskiy, lets do both? They offer different things. Do you see any reason not to?

[mvdebolskiy]

@rgknox I don't mind. Then there should be a check removed on the ClmBuildNamelist side. And in the parameter reading routine. I would #1550 should come first and then the guard rails should be lifted here.