Iteration 1: Upstream unlocking VeraCrypt partitions in GVfs

The freeze for GNOME 3.30 is on July 30 so this work must be submitted upstream early enough to ensure it’s merged by then.

The code lives in:

• https://gitlab.gnome.org/segfault3/gvfs/tree/support-tcrypt
• https://gitlab.gnome.org/segfault3/gvfs/tree/support-file-containers (that’s iteration 2 material done on #15073 (closed) but presumably it can be upstreamed at the same time)

Merge requests:
https://gitlab.gnome.org/GNOME/glib/merge_requests/120 (merged)
https://gitlab.gnome.org/GNOME/gvfs/merge_requests/4 (merged)
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/126 (merged)
https://gitlab.gnome.org/GNOME/gvfs/merge_requests/8 (merged)

Parent Task: #15214 (closed)

Related issues

• Related to #15073 (closed)
• Blocked by #15218 (closed)

Original created by @segfault on 15222 (Redmine)