* chore: build docker image with google container builder

* chore: add boilerplate header

* docs: update Readme with example usage

* docs: emphasize the fact that external-dns removes records

* ref(dnsprovider): refactor Google DNSProvider to cleaner

* ref(dnsprovider): make record transformations more efficient

* fix(dnsprovider): document that page processing is thread-safe

* in-memory dnsprovider implementation without tests

* InMemory->InMemoryProvider

* fix checks for batch change validitiy

* fix tests

* gofmt inmemory_test

* improve test coverage

* gofmt inmemory_test

use alpha annotations

route53: initial implementation of Route53 DNS provider

add once flag to exit loop after first sync

allow passing a namespace that limits found resources

better flag parse testing

ingress basic implementation

allow google provider to send requests in batches