Move environment types (globals) from flow-typed/environment to src/types (facebook#49724)

Summary:
Pull Request resolved: facebook#49724

Changelog: [internal]

This moves the type definitions for the globals defined by React Native from the repository root to the `react-native` package, in the same directory as the existing TypeScript definitions. This will make it easier for end users to configure the globals from RN using the right source of truth.

Reviewed By: huntie

Differential Revision: D70322032

fbshipit-source-id: 932df75ded0c254f2acb32e865cbbb9474c94159

Author: rubennorte

.flowconfig

@@ -41,6 +41,7 @@
 flow-typed/
 packages/react-native/interface.js
 packages/react-native/flow/
+packages/react-native/src/types/
 
 [options]
 enums=true