Iteration 1: Create custom Debian package for Disks

I backported our Disks patches to the Disks version in Stretch (#15515 (closed)).
Now we have to create a Debian package out of this, which we can ship in the beta release (planned for June 1) and Tails 3.9.

The dependencies are listed here: https://packages.debian.org/stretch/gnome-disk-utility.

Repository: https://gitlab.com/segfault3/debian-gnome-disk-utility.git
Branch: 3.22.1-1-support-tcrypt

Parent Task: #15521 (closed)

Related issues

Blocked by #15515 (closed)

Original created by @segfault on 15523 (Redmine)

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