chore(all): return concrete types, accept interfaces

- Remove exported interfaces unused locally
- Define interfaces to accept arguments
- Return concrete types, not interfaces

internal/routing/enable.go

@@ -4,10 +4,6 @@ import (
 	"fmt"
 )
 
-type Setuper interface {
-	Setup() (err error)
-}
-
 func (r *Routing) Setup() (err error) {
 	defaultRoutes, err := r.DefaultRoutes()
 	if err != nil {
@@ -40,10 +36,6 @@ func (r *Routing) Setup() (err error) {
 	return nil
 }
 
-type TearDowner interface {
-	TearDown() error
-}
-
 func (r *Routing) TearDown() error {
 	defaultRoutes, err := r.DefaultRoutes()
 	if err != nil {