func NewFormatted(base string, args ...interface{}) Composer {
	return &formatMessenger{
		base: base,
		args: args,
	}
}
NewFormatted returns a message.Composer roughly equivalent to an
fmt.Sprintf().
package message
import (
	"fmt"
	"github.com/mongodb/grip/level"
)
type formatMessenger struct {
	base    string
	args    []interface{}
	Base    `bson:"metadata" json:"metadata" yaml:"metadata"`
	Message string `bson:"message" json:"message" yaml:"message"`
}
func NewFormattedMessage(p level.Priority, base string, args ...interface{}) Composer {
	m := &formatMessenger{
		base: base,
		args: args,
	}
	_ = m.SetPriority(p)
	return m
}