Debug: add global performance function

[joshjung]

Target Code (DEV mode only):

import {performance} from 'ringa';

console.log(performance.metrics());

I envision this outputting:

• RingaObject counts (total, by Controller, by Thread, by Executor, etc.)
• Names of shortest, median, longest running threads
• Names of shortest, median, longest running executors
• Instance references to any uncaught RingaEvents
• Organized list of all failures across all threads