ARI: Retrieve existing log channels

An http request can be sent to get the existing Asterisk logs.

The command "curl -v -u user:pass -X GET 'http://localhost:8088
/ari/asterisk/logging'" can be run in the terminal to access the
newly implemented functionality.

* Retrieve all existing log channels

ASTERISK-25252

Change-Id: I7bb08b93e3b938c991f3f56cc5d188654768a808