Remove Named interface (#26913)

`Named` is implemented by every `Method` and future implementations
should implement the method too.

services/auth/basic.go

@@ -21,7 +21,6 @@ import (
 // Ensure the struct implements the interface.
 var (
 	_ Method = &Basic{}
-	_ Named  = &Basic{}
 )
 
 // BasicMethodName is the constant name of the basic authentication method