initramfs/migrate: Copy Jetson Orin boot artifact and UEFI capsule

[acostach]

Copying these files before unmounting the rootfs is needed for the case where the NVME is provisioned with a flasher image already.

If the QSPI is accessible, it will be written directly, otherwise a capsule update will be prepared by the resin-init-flasher-board script and applied by the UEFI firmware as soon as the board re-boots.

If the capsule update is interrupted on the first boot, a device specific service will attempt to re-trigger it in the next two boots.

This allows for booting flasher images directly, without entering recovery-boot mode, as long as the existing vanilla QSPI has the same BSP version as the hostOS.

Change-type: patch

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