app_queue: Add QUEUE_RAISE_PENALTY feature

Additional variable to work alongside QUEUE_MAX_PENALTY and QUEUE_MIN_PENALTY,
including an extra parameter in queuerules.conf. This value causes lower
Agent penalty values to "raise up" so that they can join higher penalty agents
and be treated equally after a period of time.

ASTERISK-26995 #close

Change-Id: If1c6421a983667a5ac4c359f6dac25b212b4c459