Functional Trait Moment Calculation // Calculates the community four 'moments' (mean, variance, skewness, and kurtosis) of a given trait based on the moments described in Wieczynski et al. (2019) doi:10.1073/pnas.1813723116. These functional metrics are extremely useful in characterizing the distribution of traits in a plant community. It also provides tidyverse- friendly wrappers to seamlessly calculate advanced functional diversity indices (e.g., FDis, Rao's Q) using 'fundiversity' (Grenie et al. 2023 doi:10.1111/ecog.06585) and functional rarity indices using 'funrar' (Grenie et al. 2017 doi:10.1111/ddi.12629). Evaluating these community-weighted moments and diversity metrics allows researchers to evaluate shifts in optimal phenotypes and understand ecological filtering with exactness.