Add centralized plotting function for DSM/DTM comparison

[Jack-Hayes]

Based on efforts for making figures for AGU 2024, we want to make a centralized plotting function to compare cascading datasets' elevations and their differences.

See old archive repo for workflow for plotting histograms of differences over different LULC classes which was adapted from the already-existing sliderule example. Also see archive repo for messy, incomplete difference map plotting. @ShashankBice has an updated notebook for plotting these difference maps.

Ideally we will have:
Standard set of 4 (10x7.5") figs total:

1. DSM settings and lidar DSM using only coincident data (standard format, 3 rows, like Shashank’s figure plus histograms)
2. Similar to 1, but with DTM results
3. DSM settings and lidar DSM using all available data, discussed in this thread
4. Similar to 3, but with DTM results

@dshean can confirm, but I believe this will be separate of to-be-implemented LiDAR and stereo DTM/DSM processing funcs. So the plotting function(s) will assume already-defined DSM/DTM variables?