Decide size of Persistent partition
Originally created by @BlueSky on #16672 (Redmine)
It would be great to be able to decide the size of the Persistent partition when creating it, so we could leave room for more partitions on the same pendrive or SD card, encrypted with different passphrases, that we might decide to only access for specific needs (I’m seeing pendrive-like USB adapters containing micro SD cards of 64 up to 1024 GB).