Delete interface.js (Flow), relocate __DEV__ global (#57275)

Summary:
Pull Request resolved: #57275

`interface.js` was a legacy, Flow-only entry point whose sole content was a bare `declare var __DEV__: boolean;` global, registered as a Flow `[libs]` file.

Relocate into `flow/globals.js`, allowing us to drop this from the package `"files"` (and `"exports"`) list.

Changelog: [Internal]

Reviewed By: rubennorte

Differential Revision: D109018822

fbshipit-source-id: 5507ff4c7c19a45980685e8691bccc998bd62107

Author: huntie

.flowconfig

@@ -39,7 +39,6 @@
 
 [libs]
 flow-typed/
-packages/react-native/interface.js
 packages/react-native/flow/
 
 [options]

packages/react-native/flow/global.js

@@ -86,3 +86,9 @@ declare var global: {
   // Undeclared properties are implicitly `any`.
   [string | symbol]: any,
 };
+
+// Declared as a bare global so unqualified `__DEV__` references type-check as
+// `boolean`. The suppression is a no-op in this checkout but avoids a duplicate
+// declaration where `__DEV__` is also declared by another Flow libdef.
+// $FlowFixMe[libdef-override]
+declare var __DEV__: boolean;

packages/react-native/interface.js

@@ -80,7 +80,6 @@
     "gradle/libs.versions.toml",
     "index.js",
     "index.js.flow",
-    "interface.js",
     "jest-preset.js",
     "Libraries",
     "LICENSE",