[Request] Remove Smart Triggers command line argument syntax and use JSON serialization

[andrewazores]

The [expr ; TargetDuration > n]~template Smart Trigger syntax should be removed along with the facility for passing these "raw" trigger definitions to the Agent via command line argument.

Instead, Smart Triggers should be created by loading from file or by remote management (both of which are already supported), and both of these should use JSON serialization of trigger definitions instead of the "square bracket, semicolon, tilde" syntax.

[andrewazores]

See also #227

[andrewazores]

See #808