chore(updater): common GetServers signature

- Log warnings when running outside of CLI mode
- Remove updater CLI bool setting
- Warnings are logged in updating functions

internal/provider/privateinternetaccess/updater/updater.go

@@ -0,0 +1,19 @@
+package privateinternetaccess
+
+import (
+	"net/http"
+)
+
+type Updater struct {
+	client *http.Client
+}
+
+type Warner interface {
+	Warn(s string)
+}
+
+func New(client *http.Client) *Updater {
+	return &Updater{
+		client: client,
+	}
+}