Revise UserSessionResolver to UserQueueSuffixResolver

The resolver for /user/{username} prefixed destinations is now
more explicitly designed to store queue suffixes rather than session
id's, which is what we happen to use as queue suffixes.

This allows something other than the sessionId to be used without
having to change many places. It also enables applications to
construct destinations with user-specific queue suffixes without
making assumptions about what's used for queue suffixes. For
example a controller may construct a map with subscription destinations
and send that down to the client.
Fix issue in MappingJacksonJsonView

Issue: SPR-10752
Replace assert w/ warning in ResourceHttpRequestHandl.

Issue: SPR-9186
Make the JSON prefix used in converters configurable

Issue: SPR-10627