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/wevpn/updater/updater.go

@@ -0,0 +1,21 @@
+package wevpn
+
+import (
+	"github.com/qdm12/gluetun/internal/updater/resolver"
+)
+
+type Updater struct {
+	presolver resolver.Parallel
+	warner    Warner
+}
+
+type Warner interface {
+	Warn(s string)
+}
+
+func New(presolver resolver.Parallel, warner Warner) *Updater {
+	return &Updater{
+		presolver: presolver,
+		warner:    warner,
+	}
+}