perf_hooks: add toJSON to performance class

Added toJSON method to the InternalPerformance class as per the
convention followed in other performance classes and per the spec:
https://www.w3.org/TR/hr-time/#tojson-method

Fixes: https://github.com/nodejs/node/issues/37623

PR-URL: https://github.com/nodejs/node/pull/37771
Fixes: https://github.com/nodejs/node/issues/37623


Reviewed-By: James M Snell <jasnell@gmail.com>