area_light_threshold: Calculate the average benthic area within light thresholds
In USGS-R/mda.lakes: Tools for combining models, data, and processing for lakes

Returns the average amount of benthic area that is within the optical intensity thresholds based on light attenuation, hypsograph, and the desired threshold values.

area_light_threshold(
  kd,
  light_incident,
  irr_thresh = c(0, 2000),
  hypso,
  area_type = "benthic",
  new_depths
)

`kd`	Light attenuation value of the lake (in m^-1 units)
`light_incident`	Vector of incident light (arbitrary units but units must match threshold units).
`irr_thresh`	Vector of length 2 with min and max value (in that order) for light thresholds. Note: >= and <= is used for comparison, so thresholds must be adjusted accordingly.
`hypso`	Hypsography data.frame, with columns `depth` and `area`. From
`area_type`	How benthic area is to be calculated. Defaults to `benthic`, which tries to estimate the slope corrected benthic area for each layer. `surface` just uses a surface area approximation, ignoring slope.
`new_depths`	Vector of depths onto which hypsography and light are calculated. This is here to enable the use of identical depths and hypsos across all calculating functions (and others are based on depths of `wtr` obs, which we don't have here.) Defaults to depths of supplied hypsography.