src: refactor and harden `ProcessEmitWarning()`

- Handle exceptions when getting `process.emitWarning` or when
  calling it properly
- Add `Maybe<bool>` to the return type, like the V8 API uses it
  to indicate failure conditions
- Update call sites to account for that and clean up/return to JS
  when encountering an error
- Add an internal `ProcessEmitDeprecationWarning()` sibling
  for use in https://github.com/nodejs/node/pull/17417,
  with common code extracted to a helper function
- Allow the warning to contain non-Latin-1 characters. Since the
  message will usually be a template string containing data passed
  from the user, this is the right thing to do.
- Add tests for the failure modes (except string creation failures)
  and UTF-8 warning messages.

PR-URL: https://github.com/nodejs/node/pull/17420
Refs: https://github.com/nodejs/node/pull/17417


Reviewed-By: Andreas Madsen <amwebdk@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>