stasis.c: Added topic_all container

Added topic_all container for centralizing the topic. This makes more
easier to managing the topics.

Added cli commands.
stasis show topics : It shows all registered topics.
stasis show topic <name> : It shows speicifed topic's detail info.

ASTERISK-28264

Change-Id: Ie86d125d2966f93de74ee00f47ae6fbc8c081c5f