Rather than an option, introduce a method and an event...
```js
server.on('stream', (stream) => {
stream.respond(undefined, { waitForTrailers: true });
stream.on('wantTrailers', () => {
stream.sendTrailers({ abc: 'xyz'});
});
stream.end('hello world');
});
```
This is a breaking change in the API such that the prior
`options.getTrailers` is no longer supported at all.
Ordinarily this would be semver-major and require a
deprecation but the http2 stuff is still experimental.
PR-URL: https://github.com/nodejs/node/pull/19959
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
