Add iface linter

Author: uudashr

.golangci.next.reference.yml

@@ -1223,15 +1223,13 @@ linters-settings:
     var-require-grouping: true
 
   iface:
-    # Identifies interfaces that are not used anywhere in the same package where the interface is defined.
-    # Default: false
-    unused: true
-    # Identifies interfaces in the same package with identical methods or constraints.
-    # Default: false
-    identical: true
-    # Identifies functions that return interfaces, but the actual returned value is always a single concrete implementation.
-    # Default: false
-    opaque: true
+    # By default set to empty. Leave it empty means all analyzers are enabled.
+    # Default: []
+    enable:
+      - unused
+      - empty
+      - duplicate
+      - opaque
 
   importas:
     # Do not allow unaliased imports of aliased packages.