Move run_has_transient_landcover function into a fire-specific module

[billsacks]

The function run_has_transient_landcover is defined here:

CTSM/src/dyn_subgrid/dynSubgridControlMod.F90

Line 350 in 2a88e90

logical function run_has_transient_landcover()

However, as noted here:

#1546 (comment)

there are subtleties about which aspects of transient landcover should and should not be included in this function. As I noted in the above comment:

I was initially concerned that you added urban to this conditional, but lake is not included. However, after some analysis of how this function is used, I think this is correct: this is just used by the fire code, which really wants to know whether there are any potential deforestation fires. Forests being replaced by urban could be linked with deforestation fires; forests being replaced by lakes / reservoirs seem very unlikely to be linked with deforestation fires.

Probably what we should do is to move this function into the fire code, and make it fire-specific, since otherwise it isn't obvious why this should include some transitions but not others.

As noted in #52 there are some broader issues with the mix of human-induced and natural landcover transitions, but those bigger issues would probably be a pain to fix, so for now I think it is sufficient to move this run_has_transient_landcover function into the fire code with comments saying that this just includes potentially human-induced aspects of landcover change.