components/metallb: Add missing autodiscovery labels

In order to allow users to control all supported BGP parameters by
specifying labels in worker pool config, we need to specify mappings
for them.

Fixes #987.

Author: johananl

pkg/components/metallb/component_test.go

@@ -265,6 +265,10 @@ component "metallb" {
     my-asn: metallb.lokomotive.io/my-asn
     peer-asn: metallb.lokomotive.io/peer-asn
     peer-address: metallb.lokomotive.io/peer-address
+    peer-port: metallb.lokomotive.io/peer-port
+    src-address: metallb.lokomotive.io/src-address
+    hold-time: metallb.lokomotive.io/hold-time
+    router-id: metallb.lokomotive.io/router-id
 address-pools:
 - name: default
   protocol: bgp

pkg/components/metallb/manifests.go

@@ -516,6 +516,10 @@ data:
         my-asn: metallb.lokomotive.io/my-asn
         peer-asn: metallb.lokomotive.io/peer-asn
         peer-address: metallb.lokomotive.io/peer-address
+        peer-port: metallb.lokomotive.io/peer-port
+        src-address: metallb.lokomotive.io/src-address
+        hold-time: metallb.lokomotive.io/hold-time
+        router-id: metallb.lokomotive.io/router-id
     address-pools:
     {{- range $k, $v := .AddressPools }}
     - name: {{ $k }}