Circular dependencies fix, hydro refactor, size/age mortality enhancement

This release includes all updates to the code since the last release at tag sci.1.27.3_api.7.3.0. The major updates include: refactoring FatesInterfaceMod into two separate modules to remove circular dependencies that was holding up a fix for E3SM; the addition of new capability in mortality of cohorts by size and age; a refactor of the hydraulics code that now results in regression tests passing; an update to grass phenology that allows grasses to drop stem in cold and drought conditions, and updates to SPITFIRE resulting in less ignitions, less area burn, and lower fire intensity to more acceptable behavior. This release also initiates the minting of a Zenodo DOI for the repository.
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