process: make tick callback and promise rejection callback more robust

- Rename `internalTickCallback` to `processTicksAndRejections`, make
  sure it does not get called if it's not set in C++.
- Rename `emitPromiseRejectionWarnings` to `processPromiseRejections`
  since it also emit events that are not warnings.
- Sets `SetPromiseRejectCallback` in the `Environment` constructor
  to make sure it only gets called once per-isolate, and make
  sure it does not get called if it's not set in C++.
- Wrap promise rejection callback initialization into
  `listenForRejections()`.
- Add comments.

PR-URL: https://github.com/nodejs/node/pull/25200


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>