Implemented the notebook for calculating Swath Width as a function of focal length.

Things to note:

1. the skew angle's default value did not change. What changed is that skew_angle is now a 2D vector instead of a scalar. B/c of this, spatial resolution now uses the skew angle in the across-track direction (i.e. skew_angle[0]). If this should be changed let me know.
2. the field-of-view vector requires slit dimensions. An arbitrary slit size was used just for demonstration purposes of the pipeline. These values will likely need to be changed
3. Swath width's default units are km, while spatial resolution's units are in m. With the current slit size and skew angles, the swath width's values (when converted to metres) are far larger than that of the spatial resolution's values, which results in a very flat plot for spatial resolution (kinda becomes meaningless to visualize). This is why I chose to plot the swath width and the spatial resolution on different graphs. I can combine them if needed