Support service log / user data / file-system encryption

[ES-Alexander]

A logical extension of #3484 - authentication prevents live access to sensitive/private data, but systems are even more secure if sensitive files are encrypted when not actively in use, so they cannot be interpreted even with direct access to the storage medium (e.g. SD card / SSD).

Note that encryption is not free, and requires computing resources in both directions, so on low end hardware is only recommended for users with data it is important to secure.

This may be more important for vehicles with direct cloud access.