*: add a mock connector which takes a username and password for testing

Since we don't have a good strategy which takes a username and password
add a mock connector which implementes PasswordConnector so we can
develop the frontend screens.

cmd/dex/config.go

@@ -111,9 +111,15 @@ func (c *Connector) UnmarshalYAML(unmarshal func(interface{}) error) error {
 
 	var err error
 	switch c.Type {
-	case "mock":
+	case "mockCallback":
 		var config struct {
-			Config mock.Config `yaml:"config"`
+			Config mock.CallbackConfig `yaml:"config"`
+		}
+		err = unmarshal(&config)
+		c.Config = &config.Config
+	case "mockPassword":
+		var config struct {
+			Config mock.PasswordConfig `yaml:"config"`
 		}
 		err = unmarshal(&config)
 		c.Config = &config.Config