#274530 by yoroy, sdboyer: Changed legacy views icons in add content modal so...

#274530 by yoroy, sdboyer: Changed legacy views icons in add content modal so they are immediately differentiable from view panes.

Superimposed 'L' onto the lower-right corner of each icon. We'll likely need to change this in the future when we refactor some of the naming schema, but it's quite adequate for now.