app_queue: Add option for predial handlers on caller and callee channels

app_queue: Add option for predial handlers on caller and callee channels

Add predial handler support to app_queue.  app_dial (ASTERISK_19548) and
app_originate (ASTERISK_26587) have the ability to execute predial
handlers on caller and callee channels.  This patch adds predial handlers
to app_queue and uses the same options as Dial and Originate (b and B).
The caller routine gets executed when the caller first enters the queue.
The callee routine gets executed for each queue member when they are about
to be called.

ASTERISK-27912

Change-Id: I5acf5c32587ee008658d12e8a8049eb8fa4d0f24