Use tempio to generate RAUC configuration files (#1797)

* Add tempio host package

tempio is a template helper using Go's template engine and sprig
functions.

* Use tempio to generate rauc manifest

* Use tempio to generate rauc system.conf

buildroot-external/ota/manifest.raucm.gtpl

@@ -0,0 +1,26 @@
+[update]
+compatible={{ env "ota_compatible" }}
+version={{ env "ota_version" }}
+
+[hooks]
+filename=hook
+hooks=install-check;
+
+[image.boot]
+filename=boot.vfat
+hooks=install;
+
+[image.kernel]
+filename=kernel.img
+{{- if eq (env "BOOTLOADER") "grub" }}
+hooks=post-install;
+{{- end }}
+
+[image.rootfs]
+filename=rootfs.img
+
+{{- if eq (env "BOOT_SPL") "true" }}
+[image.spl]
+filename=spl.img
+hooks=install
+{{- end }}

buildroot-external/ota/system.conf.gtpl

@@ -0,0 +1,45 @@
+[system]
+compatible={{ env "ota_compatible" }}
+mountprefix=/run/rauc
+statusfile=/mnt/data/rauc.db
+bootloader={{ env "BOOTLOADER" }}
+{{- if eq (env "BOOTLOADER") "grub" }}
+{{- if eq (env "BOOT_SYS") "efi" }}
+grubenv=/mnt/boot/EFI/BOOT/grubenv
+{{- else }}
+grubenv=/mnt/boot/grubenv
+{{- end }}
+{{- end }}
+
+[keyring]
+path=/etc/rauc/keyring.pem
+
+[slot.boot.0]
+device=/dev/disk/by-partlabel/hassos-boot
+type=vfat
+allow-mounted=true
+{{- if eq (env "BOOT_SPL") "true" }}
+[slot.spl.0]
+device=/dev/disk/by-partlabel/hassos-boot
+type=raw
+{{- end }}
+
+[slot.kernel.0]
+device=/dev/disk/by-partlabel/hassos-kernel0
+type=raw
+bootname=A
+
+[slot.rootfs.0]
+device=/dev/disk/by-partlabel/hassos-system0
+type=raw
+parent=kernel.0
+
+[slot.kernel.1]
+device=/dev/disk/by-partlabel/hassos-kernel1
+type=raw
+bootname=B
+
+[slot.rootfs.1]
+device=/dev/disk/by-partlabel/hassos-system1
+type=raw
+parent=kernel.1