Code review comment for ~info-martin-konrad/epics-base:callbackQueueStatus

Merging this, but one change I've made is to rename your QueuePrintStatus() routines and the QueueStatus iocsh commands (and their associated routines and data structures) to QueueShow for consistency with other subsystems. We normally use a Show suffix for routines that print stuff to stdout, and Status for querying whether a subsystem is happy, so your QueueStatus() API routines are fine. This is also necessary to maintain command-line compatibility with the VxWorks shell.