cut mask (experiment footprint) based on input keyword

[syasini]

Currently, the canvas.cut_mask() method takes in the healpix map of an experiment footprint. It would be nice to allow the user to apply such cuts using experiment footprints. For example

canvas.cut_mask("CMB-S4", inplace=True) 
canvas.cut_mask("DESI", inplace=True) 

would limit the catalog to the common footprint between S4 and DESI.

TODO: Add masks from cmb x galaxy web app to the data directory.