internal/rosa/package: migrate initramfs image

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/package/images/initramfs

@@ -0,0 +1,4 @@
+dir /dev 0755 0 0
+nod /dev/null 0666 0 0 c 1 3
+nod /dev/console 0600 0 0 c 5 1
+file /init /usr/src/initramfs-image/earlyinit 0555 0 0

internal/rosa/package/images/package.az

@@ -0,0 +1,21 @@
+package initramfs-image {
+	description = "Rosa OS initramfs image";
+	version = unversioned;
+	exclude = true;
+
+	source = earlyinit;
+	files = {
+		"initramfs";
+	};
+	exec = generic {
+		build = "gen_init_cpio "+
+			"-t 4294967295 "+
+			"-c /usr/src/initramfs | "+
+			"zstd > /work/initramfs.zst";
+	};
+
+	inputs = [
+		zstd,
+		gen_init_cpio,
+	];
+}