Iteration 2: Show unlocked VeraCrypt file containers in GtkPlacesSidebar

Originally created by @segfault on #15225 (Redmine)

Development repository: https://github.com/segfault3/gtk
Branch: gtk-3-22_add_loop_and_dm_to_sidebar

Parent Task: #15223 (closed)

Related issues

Edited by segfault
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information