Automatic merge from submit-queue

federation: fix dns provider initialization issues

This PR is based on the integration test with Google DNS API. This is the first time of full integration test.
So multiple issues was found and I combined all of them in this single PR

1. add dns provider initialization and add ensureDns call when removing federation service.
2. add new flags federation-name and zone-name to controller manager, both are used as part of the dns record name
3. fix assertion failure at rrsets.go#L61, which will cause panic
4. change getFederationDNSZoneName to get zoneName from config instead of hard code
5. change logic of ensureDnsRrsets, only add new dns record when endpointReachable(set to true when ready address is catched) is true
6. fix bug in processEndpointUpdate, only call ensuredns when ready address is caught
7. change behavior of syncService, there is cases that endpoint is created before ingress IP assignment, so before there is defect for this case, ensureDns was not called when service being updated, so if Ingress IP is assigned after endpoint ready address is caught, the corresponding A records can not be created
8. add a checking before update federation service

@nikhiljindal , can you help to add 1.3 milestone when @quinton-hoole is on leave?
Thanks.

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