process: improve process.hrtime

* Add benchmarks for diffing a previous result
* Improvements to the documentation, including type annotation
* Update the outdated comments in src/node.cc, improve comments
  in lib/internal/process.js
* Check the argument is an Array Tuple with length 2

PR-URL: https://github.com/nodejs/node/pull/10764


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Brian White <mscdex@mscdex.net>