[v12.x backport] src: improve embedder API

It’s been a while since these have landed on v14.x, so we should have had enough baking time to backport these:

• https://github.com/nodejs/node/pull/30467 – src: improve embedder API
• https://github.com/nodejs/node/pull/32563 – test: wait for message from parent in embedding cctest
• https://github.com/nodejs/node/pull/32531 – embedding: provide hook for custom process.exit() behaviour
• https://github.com/nodejs/node/pull/32406 – test: use InitializeNodeWithArgs in cctest
• https://github.com/nodejs/node/pull/32422 – test: use common.buildType in embedding test
• https://github.com/nodejs/node/pull/32672 – src: initialize inspector before RunBootstrapping()
• https://github.com/nodejs/node/pull/33084 – worker: unify custom error creation
• https://github.com/nodejs/node/pull/32523 – src: use env’s instead of isolate’s RequestInterrupt() + v8::Platform
• https://github.com/nodejs/node/pull/34366 – src: add callback scope for native immediates
• https://github.com/nodejs/node/pull/34751 – test,doc: add missing uv_setup_args() calls

There were no major conflicts to be resolved, mostly neighbouring-line conflicts. (Non-conflict changes that were necessary for backporting are in the fixup! commits.)

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