lib/ClimaLandSimulations functions instead of include

[AlexisRenchon]

Is your feature request related to a problem? Please describe. ClimaLandSimulations allows running ClimaLSM for FLUXNET sites, but currently include path to configuration files (domain, timestepper, parameters...). While it works, this is not very elegant. This SDI will refactor the code to use functions instead of includes.

PR #457