Migrate kafka-operator to use lb-operator for exposing brokers

[nightkr]

Description

This is far from final (for example, we'd need to expose a configurable LoadBalancerClass, for example), but I wanted to see whether lb-op would be a good fit for this operator first.

Review Checklist

• [ ] Code contains useful comments
• [ ] CRD change approved (or not applicable)
• [ ] (Integration-)Test cases added (or not applicable)
• [ ] Documentation added (or not applicable)
• [ ] Changelog updated (or not applicable)
• [ ] Cargo.toml only contains references to git tags (not specific commits or branches)
• [ ] Helm chart can be installed and deployed operator works (or not applicable)

Once the review is done, comment bors r+ (or bors merge) to merge. Further information