Add some testmods for FATES to test some different FATES parameter file options

[ekluzek]

As a first step in moving toward #2126 we want to create some testmod directories with shell_commands that do ncgen on the FATES cdl file and then modify it using the FATES tools in order to test some different switches on the FATES parameter file.

Definition of Done:

• @glemieux updates Add FATES cross-grid seed dispersal mechanism #2077
• @adrifoster tries running with all the different options on all at once ("kitchen sink" test) and make sure it doesn't blow up
• @adrifoster PR for new testmods for all the options
• @rgknox add testmod to forthcoming two-stream Fates two stream API  #2265

[ekluzek]

It would be good to show proof of concept for this by doing a simple PR that just adds one simple testmod with the simplest modification possible.

[glemieux]

The upcoming seed dispersal PR #2077 will be a good use of this.

Also size and age dependent mortality have undefined values in the default parameter file and don't engage until they've been given reasonable values.

@rgknox would the different model switches in the parameter file (e.g. fates_maintresp_leaf_model, fates_regeneration_model, etc) be good candidates to test as well?

[rgknox]

We have a bunch of module switches that would be good candidates. I'm ordering these in order of complexity, I think its best to get tests going on those that have the most complexity. The regeneration model, especially with the light mortality dynamics is the most complicated.

fates_regeneration_model
fates_leaf_photo_tempsens_model
fates_allom_fnrt_prof_mode
fates_hydro_htftype_node (UPDATE: maybe avoid this one in the first set)
fates_rad_model (Note: not on fates main branch yet)

fates_maintresp_leaf_model
fates_leaf_stomatal_model

fates_leaf_stomatal_assim_model

It would be nice to test these in the future for longer tests
fates_maxcohort
fates_maxpatch_primary

[glemieux]

During discussion today @rgknox noted that if we address #1277 we could reduce the time to stress test some of the run modes that need more structure.

Also see NGEET/fates#846 and #1685

[glemieux]

Per discussion today, we agreed that we should try and create a PR to develop testmods of all of the above with the exception of the long term tests (maxpatch) and hydro. @rgknox to add the relevant testmod to the API update that will come along with two-stream.

[ekluzek]

@glemieux thanks for the list of tasks from the discussion. To make it easier to see, I'm going to move it to the top and add it as "definition of done".

[glemieux]

Item 1 in the definition of done will be complete via 2896889