Create NativeModuleSchema and ComponentSchema

Summary:
NOTE: Flow and Jest won't pass on this diff. Sandcastle, should, however, be green on D24236405 (i.e: the tip of this stack).

## Description
The Codegen deals with "Modules". Hence:
```
type SchemaType = {
  modules: {
    [moduleName]: ...
  }
};
```

Each "Module" has a name, and represents a file. The `moduleName` is the base name of the file. This file can contain a component specification or a NativeModule specification. Hence:

```
type SchemaType = {
  modules: {
    [moduleName]: ComponentSchema | NativeModuleSchema
  }
};
```

The `ComponentSchema` can contain specifications for many different components. Hence:

```
type ComponentSchema = {
  type: 'Component'
  components: {
    [componentName]: ComponentShape
  }
}
```

The `NativeModuleSchema` contains
1. Type aliases (no surprises/nothing new).
2. One Flow interface that extends `TurboModule`.
3. Potentially many different NativeModule requires (for now) via `TurboModuleRegistry.get(Enforcing)?<specName>('moduleName')`.

Hence, the shape looks like:
```
type NativeModuleSchema = {
  type: 'NativeModule',
  aliases: NativeModuleAliasMap, // nothing new
  spec: NativeModuleSpec,
  moduleNames: $ReadOnlyArray<string>
}

type NativeModuleSpec = {
  properties: $ReadOnlyArray<...>,
}
```

## Major Notes
1. We now parse the NativeModule requires (TurboModuleRegistry.get(Enforcing)?<Spec> calls) and record them in the schema.
2. A Codegen "Module" can contain either a Component schema, or a NativeModule schema, but **not** both.

## Snapshot Updates
The changes to the schema are visible in the snapshots updated in D24236505.

Changelog: [Internal]

(Note: this ignores all push blocking failures!)

Reviewed By: fkgozali

Differential Revision: D24236510

fbshipit-source-id: bd344d67136418725d840e7332fd2f6957326bb4

packages/react-native-codegen/src/CodegenSchema.js

@@ -244,24 +244,29 @@ export type ComponentShape = $ReadOnly<{|
 |}>;
 
 export type SchemaType = $ReadOnly<{|
-  modules: $ReadOnly<{
-    [module: string]: $ReadOnly<{|
-      components?: $ReadOnly<{[component: string]: ComponentShape, ...}>,
-      nativeModules?: $ReadOnly<{
-        [nativeModule: string]: NativeModuleSchema,
-        ...,
-      }>,
-    |}>,
-    ...,
-  }>,
+  modules: $ReadOnly<{|
+    [moduleName: string]: ComponentSchema | NativeModuleSchema,
+  |}>,
+|}>;
+
+export type ComponentSchema = $ReadOnly<{|
+  type: 'Component',
+  components: $ReadOnly<{|
+    [componentName: string]: ComponentShape,
+  |}>,
 |}>;
 
 /**
  * NativeModule Types
  */
 export type NativeModuleSchema = $ReadOnly<{|
-  // We only support aliases to Objects
+  type: 'NativeModule',
   aliases: NativeModuleAliasMap,
+  spec: NativeModuleSpec,
+  moduleNames: $ReadOnlyArray<string>,
+|}>;
+
+type NativeModuleSpec = $ReadOnly<{|
   properties: $ReadOnlyArray<NativeModulePropertySchema>,
 |}>;