GLFC-WET/hydroweight: Hydroweight modernization updates

The hydroweight updates represented a major internal modernization aimed at computational performance, reliability, and maintainability, while keeping the external workflow familiar per the past stable release of the R package. Major pull requests from other users were examined and integrated into the package. New package documentation was completed with a revised tutorial that focuses on more straightforward execution of the functions as well as implications of choices (e.g., weighting schemes) made by users.