Tidy up several things in build files (#3)

Change from QCow2 to Raw images
Update boot options for better outputs
Add SSH host key acceptance files
Change Ubuntu builder to Ubuntu 22

sources/qemu.pkr.hcl

@@ -1,20 +1,30 @@
+variable "qemu_accelerator" {
+	type = string
+	default = "kvm"
+}
+
 source "qemu" "x86_64" {
 	iso_url = var.iso.url
 	iso_checksum = var.iso.checksum
-	output_directory = "output_${local.name}"
-	vm_name = "packer-${local.name}"
-	disk_size = var.disk_size
-	boot_wait = var.boot_wait
-	ssh_timeout = "358m"
-	ssh_username = var.ssh.username
-	ssh_password = var.ssh.password
-	headless = var.headless
+	output_directory = "output_qemu_${local.name}"
+
 	boot_command = var.boot_command
-	http_directory = "http"
-	ssh_handshake_attempts = var.ssh_handshake_attempts
-	accelerator = var.qemu_accelerator
-	cpus = 2
-	memory = 2048
-	qemuargs = [["-serial", "stdio"]]
 	shutdown_command = var.shutdown_command
+	boot_wait = var.boot_wait
+	ssh_timeout = local.ssh.timeout
+	ssh_username = local.ssh.username
+	ssh_password = local.ssh.password
+	ssh_handshake_attempts = local.ssh.handshake_attempts
+
+	vm_name = "packer-${local.name}"
+	disk_size = "${local.disk_size}G"
+	cpus = local.cpus
+	memory = local.memory
+	headless = var.headless
+	disk_cache = "writeback"
+	format = "qcow2"
+
+	qemuargs = [["-serial", "stdio"]]
+	http_directory = "http"
+	accelerator = var.qemu_accelerator
 }