Operator: targetKafkaServiceRefNaming

[robobario]

While we're touching KafkaService we should decide what language we want in the VirtualKafkaCluster, currently it's targetKafkaServiceRef

would proxiedKafkaServiceRef be more easily understood by users? Target introduces another concept.

Originally posted by @robobario in #61 (comment)

Tom:

The comment above is # Points to the cluster being proxied. It's interesting that such an explanation is necessary, and that that's the language we use there.

SamBarker:

For me target encapsulates what it actually and I think fairly obvious what it means. My other hesitation is proxiedKafkaService is the result of applying the CRs so feels like a more natural name for a thing describing how to connect to Kafka via the proxy.

But I can certainly see proxiedKafkaServiceRef as being easier to understand when just reading a CR without any context.

That said the terminology we use in the proxy is upstream so to be consistent it should be upstreamKafkaServerRef

Tom:

Would be more compelling if we actually liked that terminology. But we've questioned it in the past, so...
Also that terminology is usually used in a slightly different context: where we have two connections and want to distinguish them with a single qualifier and it's desirable for the one qualifier to be "the opposite" of the other. In contexts like this one we don't use the term "downstream cluster".