Podman 5 machine config file - Step 1

The following PR is the very first step in what will a series of steps
to apply a "common" machine configuration file to all providers.
Function names, method names, struct names, and field names are all up
for debate.  The purpose of this PR is to offer a glimpse at the
direction we intend to take.

This PR also contains temporary structs (i.e. aThing) that are not
exported.  These are merely placeholders.

The configuration work in this PR is also unused of yet.  But the code
is compiled.  Once merged, we can begin the next step of development.

[NO NEW TESTS NEEDED]

Signed-off-by: Brent Baude <bbaude@redhat.com>

pkg/machine/qemu/command/qemu_command_test.go

@@ -0,0 +1,67 @@
+//go:build (amd64 && !windows) || (arm64 && !windows)
+// +build amd64,!windows arm64,!windows
+
+package command
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/containers/podman/v4/pkg/machine/define"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestQemuCmd(t *testing.T) {
+	ignFile, err := define.NewMachineFile(t.TempDir()+"demo-ignition-file.ign", nil)
+	assert.NoError(t, err)
+
+	machineAddrFile, err := define.NewMachineFile(t.TempDir()+"tmp.sock", nil)
+	assert.NoError(t, err)
+
+	readySocket, err := define.NewMachineFile(t.TempDir()+"readySocket.sock", nil)
+	assert.NoError(t, err)
+
+	vmPidFile, err := define.NewMachineFile(t.TempDir()+"vmpidfile.pid", nil)
+	assert.NoError(t, err)
+
+	monitor := Monitor{
+		Address: *machineAddrFile,
+		Network: "unix",
+		Timeout: 3,
+	}
+	ignPath := ignFile.GetPath()
+	addrFilePath := machineAddrFile.GetPath()
+	readySocketPath := readySocket.GetPath()
+	vmPidFilePath := vmPidFile.GetPath()
+	bootableImagePath := t.TempDir() + "test-machine_fedora-coreos-38.20230918.2.0-qemu.x86_64.qcow2"
+
+	cmd := NewQemuBuilder("/usr/bin/qemu-system-x86_64", []string{})
+	cmd.SetMemory(2048)
+	cmd.SetCPUs(4)
+	cmd.SetIgnitionFile(*ignFile)
+	cmd.SetQmpMonitor(monitor)
+	cmd.SetNetwork()
+	cmd.SetSerialPort(*readySocket, *vmPidFile, "test-machine")
+	cmd.SetVirtfsMount("/tmp/path", "vol10", "none", true)
+	cmd.SetBootableImage(bootableImagePath)
+	cmd.SetDisplay("none")
+
+	expected := []string{
+		"/usr/bin/qemu-system-x86_64",
+		"-m", "2048",
+		"-smp", "4",
+		"-fw_cfg", fmt.Sprintf("name=opt/com.coreos/config,file=%s", ignPath),
+		"-qmp", fmt.Sprintf("unix:%s,server=on,wait=off", addrFilePath),
+		"-netdev", "socket,id=vlan,fd=3",
+		"-device", "virtio-net-pci,netdev=vlan,mac=5a:94:ef:e4:0c:ee",
+		"-device", "virtio-serial",
+		"-chardev", fmt.Sprintf("socket,path=%s,server=on,wait=off,id=atest-machine_ready", readySocketPath),
+		"-device", "virtserialport,chardev=atest-machine_ready,name=org.fedoraproject.port.0",
+		"-pidfile", vmPidFilePath,
+		"-virtfs", "local,path=/tmp/path,mount_tag=vol10,security_model=none,readonly",
+		"-drive", fmt.Sprintf("if=virtio,file=%s", bootableImagePath),
+		"-display", "none"}
+
+	require.Equal(t, cmd.Build(), expected)
+}