dillon1000/react

[Fizz] New Server Rendering Infra (#14144)

* [Fizz] Add Flow/Jest/Rollup build infra

Add a new package for react-stream which allows for custom server renderer
outputs. I picked the name because it's a reasonable name but also
because the npm name is currently owned by a friend of the project.

The react-dom build has its own inlined server renderer under the
name `react-dom/fizz`.

There is also a noop renderer to be used for testing. At some point
we might add a public one to test-renderer but for now I don't want to have
to think about public API design for the tests.

* Add FormatConfig too

We need to separate the format (DOM, React Native, etc) from the host
running the server (Node, Browser, etc).

* Basic wiring between Node, Noop and DOM configs

The Node DOM API is pipeToNodeStream which accepts a writable stream.

* Merge host and format config in dynamic react-stream entry point

Simpler API this way but also avoids having to fork the wrapper config.

Fixes noop builds.

* Add setImmediate/Buffer globals to lint config

Used by the server renderer

* Properly include fizz.node.js

Also use forwarding to it from fizz.js in builds so that tests covers
this.

* Make react-stream private since we're not ready to publish

or even name it yet

* Rename Renderer -> Streamer

* Prefix react-dom/fizz with react-dom/unstable-fizz

* Add Fizz Browser host config

This lets Fizz render to WHATWG streams. E.g. for rendering in a
Service Worker.

I added react-dom/unstable-fizz.browser as the entry point for this.

Since we now have two configurations of DOM. I had to add another
inlinedHostConfigs configuration called `dom-browser`. The reconciler
treats this configuration the same as `dom`. For stream it checks
against the ReactFizzHostConfigBrowser instead of the Node one.

* Add Fizz Browser Fixture

This is for testing server rendering - on the client.

* Lower version number to detach it from react-reconciler version