bug: dnspolicy record controller panics if no name on listener

[maleck13]

create a gateway with a listener that has no hostname
DNSPolicy will not get reconciled as it hits a nil pointer

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager panic: runtime error: invalid memory address or nil pointer dereference
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager [signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x15995dc]
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager goroutine 661 [running]:
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile.func1()
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager /go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:111 +0x1a4
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager panic({0x183a240?, 0x2fee490?})
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager /usr/local/go/src/runtime/panic.go:770 +0x124
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager github.com/kuadrant/kuadrant-operator/controllers.(*DNSPolicyReconciler).reconcileGatewayDNSRecords(0x400065ba10, {0x1e9bad8, 0x4000b04600}, 0x40004af380, 0x40004ae000)
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager /workspace/controllers/dnspolicy_dnsrecords.go:60 +0x23c
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager github.com/kuadrant/kuadrant-operator/controllers.(*DNSPolicyReconciler).reconcileDNSRecords(0x400065ba10, {0x1e9bad8, 0x4000b04600}, 0x40004ae000, 0x40007dc4b0)
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager /workspace/controllers/dnspolicy_dnsrecords.go:38 +0x424
kuadrant-operator-controller-manager-8566585ffc-gqr66 manager github.com/kuadrant/kuadrant-operator/controllers.(*DNSPolicyReco