Introduce ObjectTypeAnnotation utility type

Summary:
All throughout the Codegen schema, we re-declare the following shape:
```
{
  type: 'ObjectTypeAnnotation',
  properties: $ReadOnlyArray<{
    name: string,
    optional: boolean,
    typeAnnotation: ...
  }>
}
```

This diff introduces an `ObjectTypeAnnotation<T>` utility type and replaces those re-declarations with instantiations of this type.

**Motivation:** To reduce noise in the CodegenSchema. This should be a pure refactor, and shouldn't actually change any behaviour.

Changelog: [Internal]

Reviewed By: yungsters

Differential Revision: D24707963

fbshipit-source-id: 6b4eb711ddd041f3a041109ade5ad5644fb16924

packages/react-native-codegen/src/generators/components/GeneratePropsJavaInterface.js

@@ -11,9 +11,10 @@
 'use strict';
 
 import type {
-  CommandTypeShape,
+  NamedShape,
+  CommandsTypeAnnotation,
   ComponentShape,
-  PropTypeShape,
+  PropTypeAnnotation,
   SchemaType,
 } from '../../CodegenSchema';
 const {
@@ -47,7 +48,10 @@ function addNullable(imports) {
   imports.add('import androidx.annotation.Nullable;');
 }
 
-function getJavaValueForProp(prop: PropTypeShape, imports): string {
+function getJavaValueForProp(
+  prop: NamedShape<PropTypeAnnotation>,
+  imports,
+): string {
   const typeAnnotation = prop.typeAnnotation;
 
   switch (typeAnnotation.type) {
@@ -153,7 +157,7 @@ function getCommandArgJavaType(param) {
 }
 
 function getCommandArguments(
-  command: CommandTypeShape,
+  command: NamedShape<CommandsTypeAnnotation>,
   componentName: string,
 ): string {
   return [