Unencrypt a garlic message and handle each of the cloves - locally destined
messages are tossed into the inbound network message pool so they're handled
as if they arrived locally.
Receive a request to join a tunnel, and if we aren't overloaded (per the
throttle), join it (updating the tunnelDispatcher), then send back the
agreement.
Defines a class that builds jobs to handle a particular message - these
builders are registered with the InNetMessagePool for various I2NP message
types, allowing immediate queueing of a handler job rather than waiting for
a polling job to come pick it up.