Support unlocking with VeraCrypt keyfiles in udisks
During the UX sprint we decided that we must support unlocking with keyfiles, because it is an often used feature (43% of survey participants).
This is already supported by cryptsetup, so we will have to patch libblockdev and udisks for this.
Parent Task: #6337 (closed)
Original created by @segfault on 15046 (Redmine)