Set RequestLog#content for AnnotatedService if a pojo is requested/returned

[jrhee17]

Logging[Client|Service] can be confusing since the request/response content is sometimes logged, and sometimes not logged.

Request/Responses are logged when:

• GrpcService or ThriftService is used
• ContentPreviewing[Client|Service] is used

The majority of our users use AnnotatedService along with GrpcService or ThriftService.
However, when adding a Logging[Client|Service] to APIs, it may be surprising that some services log content by default while others don't.

In most cases, this isn't a big problem. However, we recently saw a case where a service handling sensitive data used AnnotatedService and intentionally didn't add a ContentPreviewing[Client|Service]. While adopting GrpcService, they found that sensitive information was being logged by default.

I believe if we just log content for AnnotatedService by default as well, users can be aware that content will be left in most cases and configure Logging[Client|Service] accordingly. As an added bonus, by leaving the POJO at RequestLog#content we may potentially also allow users to sanitize specific fields more easily.