[v6.x backport] src: add environment cleanup hooks

[gabrielschulhof]

This adds pairs of methods to the Environment class and to public APIs
which can add and remove cleanup handlers.

Unlike AtExit, this API targets addon developers rather than
embedders, giving them (and Node’s internals) the ability to register
per-Environment cleanup work.

We may want to replace AtExit with this API at some point.

Many thanks for Stephen Belanger for reviewing the original version of
this commit in the Ayo.js project.

Refs: ayojs/ayo#82
PR-URL: #19377

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines