src: inspector context name = program title + pid

Report (for example) "node[1337]" as the human-readable name rather
than the more generic and less helpful "Node.js Main Context."

While not perfect yet, it should be an improvement to people that
debug multiple processes from DevTools, VS Code, etc.

PR-URL: https://github.com/nodejs/node/pull/17087


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>