chore(all): return concrete types, accept interfaces

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

internal/provider/perfectprivacy/updater/updater.go

@@ -1,17 +1,15 @@
 package updater
 
-import "github.com/qdm12/gluetun/internal/updater/unzip"
+import (
+	"github.com/qdm12/gluetun/internal/provider/common"
+)
 
 type Updater struct {
-	unzipper unzip.Unzipper
-	warner   Warner
+	unzipper common.Unzipper
+	warner   common.Warner
 }
 
-type Warner interface {
-	Warn(s string)
-}
-
-func New(unzipper unzip.Unzipper, warner Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner) *Updater {
 	return &Updater{
 		unzipper: unzipper,
 		warner:   warner,