Resolve host configs at build time (#12792)

* Extract base Jest config

This makes it easier to change the source config without affecting the build test config.

* Statically import the host config

This changes react-reconciler to import HostConfig instead of getting it through a function argument.

Rather than start with packages like ReactDOM that want to inline it, I started with React Noop and ensured that *custom* renderers using react-reconciler package still work. To do this, I'm making HostConfig module in the reconciler look at a global variable by default (which, in case of the react-reconciler npm package, ends up being the host config argument in the top-level scope).

This is still very broken.

* Add scaffolding for importing an inlined renderer

* Fix the build

* ES exports for renderer methods

* ES modules for host configs

* Remove closures from the reconciler

* Check each renderer's config with Flow

* Fix uncovered Flow issue

We know nextHydratableInstance doesn't get mutated inside this function, but Flow doesn't so it thinks it may be null.
Help Flow.

* Prettier

* Get rid of enable*Reconciler flags

They are not as useful anymore because for almost all cases (except third party renderers) we *know* whether it supports mutation or persistence.

This refactoring means react-reconciler and react-reconciler/persistent third-party packages now ship the same thing.
Not ideal, but this seems worth how simpler the code becomes. We can later look into addressing it by having a single toggle instead.

* Prettier again

* Fix Flow config creation issue

* Fix imprecise Flow typing

* Revert accidental changes

scripts/shared/inlinedHostConfigs.js

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+'use strict';
+
+module.exports = [
+  {
+    shortName: 'dom',
+    entryPoints: ['react-dom'],
+    isFlowTyped: true,
+  },
+  {
+    shortName: 'art',
+    entryPoints: ['react-art'],
+    isFlowTyped: false, // TODO: type it.
+  },
+  {
+    shortName: 'native',
+    entryPoints: ['react-native-renderer'],
+    isFlowTyped: true,
+  },
+  {
+    shortName: 'fabric',
+    entryPoints: ['react-native-renderer/fabric'],
+    isFlowTyped: true,
+  },
+  {
+    shortName: 'test',
+    entryPoints: ['react-test-renderer'],
+    isFlowTyped: true,
+  },
+  {
+    shortName: 'custom',
+    entryPoints: ['react-reconciler', 'react-reconciler/persistent'],
+    isFlowTyped: true,
+  },
+];