Images recipes for Raspberry Pi 64b

Added recipes for RPi 3/4 in 64b mode booted via u-boot -- both for APT and ostree images.

Added gitlab-ci to integrate images into pipeline. No tests added since we have no test boards in LAVA.

Generated images tested manually.

apertis-ostree-commit.yaml

@@ -27,6 +27,19 @@ actions:
     description: "Install ed25519 public keys"
     source: overlays/ed25519
 
+{{ if eq $architecture "arm64" }}
+  - action: apt
+    description: U-Boot package
+    packages:
+      - u-boot-rpi
+
+  - action: apt
+    description: Firmware packages
+    packages:
+      - raspi-firmware
+      - firmware-brcm80211
+{{ end }}
+
   - action: apt
     description: Kernel and system packages
     packages: