fix: support calling onClose multiple times in edge-ssr-app (#81911)
#81389 changed the implementation of `edge-ssr-app`. it added a
`RenderOpts.onClose` implemented like this:
```ts
let onCloseCallback: (() => void) | undefined
const renderOpts = {
// ...
onClose: (cb) => {
onCloseCallback = cb
},
}
```
this does not match the behavior of the node implementations of
`onClose`, which use `res.on('close', cb)` -- calling this `onClose`
multiple times won't work right, because we'll only store the last
callback.
in practice we currently only call `onClose` once per request, in
`AfterContext`, so this *technically works*. but that might change in
the future, and it'd break things in surprising ways. to avoid this, i'm
changing it to use `CloseController`, which we're already using in other
places that need to implement this behavior.
next.js
a21b68ab - fix: support calling onClose multiple times in edge-ssr-app (#81911)
