Message Formatting function for assert package

This should make it easier to have fmt style formatted messages in the assertions.

assert/message.go

@@ -1,7 +1,13 @@
 package assert
 
+import "fmt"
+
 type Message string
 
+func MessageF(format string, args ...any) Message {
+	return Message(fmt.Sprintf(format, args...))
+}
+
 func toMsg(msg []Message) []any {
 	var out []any
 	for _, m := range msg {

assert/message_test.go

@@ -22,3 +22,8 @@ func TestMessage(t *testing.T) {
 	a.True(false, exp)
 	assert.Contain(t, dtb.Logs.String(), strings.TrimSpace(string(exp)))
 }
+
+func TestMessagef(t *testing.T) {
+	exp := assert.MessageF("answer:%d", 42)
+	assert.Equal[assert.Message](t, exp, "answer:42")
+}