feat: mvp (#1)

MVP including features:
* Detect IP change
* Configurable/generic external IP provider
* Configurable/generic DNS provider
* Impl. of plain external IP provider
* Impl. of Ionos DNS provider

Reviewed-on: #1
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

pkg/externalIpProvider/externalIpProvider.go

@@ -0,0 +1,9 @@
+package externalIpProvider
+
+import (
+	"net"
+)
+
+type ExternalIpProvider interface {
+	GetExternalIp() (net.IP, error)
+}