Fix DDNS bugs and split up ddns module (#326)

* fix: webhook retry logic
fix: adjust record type based on ipv4 ipv6
refract: move ddns providers to a new module

* refract: move ddns module to pkg/

pkg/ddns/ddns.go

@@ -0,0 +1,14 @@
+package ddns
+
+type DomainConfig struct {
+	EnableIPv4 bool
+	EnableIpv6 bool
+	FullDomain string
+	Ipv4Addr   string
+	Ipv6Addr   string
+}
+
+type Provider interface {
+	// UpdateDomain Return is updated
+	UpdateDomain(domainConfig *DomainConfig) bool
+}