[Story] Smart Triggers API

[andrewazores]

One idea for this could be an API endpoint for creating and querying smart triggers, for example

endpoint /triggers/

GET - returns a serialization of the currently active triggers, e.g.

GET /triggers/
{trigger : "[processCpuLoad>0.2]~Profiling"}

POST - parse and apply a trigger definition from the given argument

This would allow users to define triggers via the API and would also allow us to create a UI in cryostat-web for viewing and creating them which would improve the user experience quite a bit.
@Josh-Matsuoka in #225