Support Node 20

[HitkoDev]

process.send is no longer accessible from ESM loader in Node 20, therefore loader needs to use context.port and a proxy function to send messages to the parent. See https://nodejs.org/api/esm.html#globalpreload

--experimental-specifier-resolution has been removed in Node 19 (https://github.com/nodejs/node/pull/44859), so the test for it is no longer relevant.

[olivierchatry]

Would be really great if we can get that PR in and get a version publish !