Draft: Add rauc

Add initial rauc support.

I`ve addressed most of the requests, but there are some notes:

• Following MR seco-ne/yocto/manifest!1397 (merged) is blocking auto pipelines execution.
• Following change is also needed: meta-seconorth-machine!463 (closed)
• only seconorth-image is supported for now
• keys and certificates needs to be added manually into the layers for now
• it needs to be defined how bundle versioning will be done in the future
• dependency between rauc service and /etc/shared being mounted is not properly checked (it seems to be working right now)
• partitions are hardcoded for now (there is an issue with labels, which needs to be fixed first)
• current postinstallation scripts, which in turn call fnginstall-postinstallation poorly handle bootB.cfg and bootB.scr.
• some script from fnginstall-postinstallation deletes "LINUXB" and "ROOTFSB" labels from partitions.

We are working on last two items now.