Feature/Include Water Observations and add dynamic range colorbar for xch4 plots

[laestrada]

Name and Institution (Required)

Name: Lucas Estrada Institution: Harvard ACMG

Describe the update

This update:

• adds a config variable UseWaterObs to toggle on use of glint observations taken over water.
• adds a dynamic colorbar to plots of xch4
• sets the facecolor to "none" for cartopy layers, fixing an issue where observations or state vector elements over water would not be displayed in plots
• removes use of the glasbey colormap, as this led to odd rendering with large state vectors
• documentation updates