Add explicit types for Types and Properties in LayoutAnimation (#48728)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/48728

Changelog:
[General][Changed] - Improved types for exported Types and Properties in LayoutAnimation

Reviewed By: rshest

Differential Revision: D68270119

fbshipit-source-id: 7e9e6e6f20b6c17990b40d423eb4571807004b49

packages/react-native/Libraries/LayoutAnimation/LayoutAnimation.js

@@ -174,13 +174,13 @@ const LayoutAnimation = {
     easeIn: 'easeIn',
     easeOut: 'easeOut',
     keyboard: 'keyboard',
-  }),
+  }) as $ReadOnly<{[K in LayoutAnimationType]: K}>,
   Properties: Object.freeze({
     opacity: 'opacity',
     scaleX: 'scaleX',
     scaleY: 'scaleY',
     scaleXY: 'scaleXY',
-  }),
+  }) as $ReadOnly<{[K in LayoutAnimationProperty]: K}>,
   checkConfig(...args: Array<mixed>) {
     console.error('LayoutAnimation.checkConfig(...) has been disabled.');
   },

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -5635,8 +5635,8 @@ declare const Presets: {
 declare const LayoutAnimation: {
   configureNext: configureNext,
   create: create,
-  Types: $FlowFixMe,
-  Properties: $FlowFixMe,
+  Types: $ReadOnly<{ [K in LayoutAnimationType]: K }>,
+  Properties: $ReadOnly<{ [K in LayoutAnimationProperty]: K }>,
   checkConfig(...args: Array<mixed>): void,
   Presets: Presets,
   easeInEaseOut: (onAnimationDidEnd?: OnAnimationDidEndCallback) => void,