RN: Flowify scripts (#51780)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51780

Adds `flow` to the remaining files that are lacking it (or `noflow`) in the `scripts` directory.

This also fixes what I believe to be a typo in one of the files.

Changelog:
[Internal]

Reviewed By: SamChou19815

Differential Revision: D75883851

fbshipit-source-id: 928b7a12a08269b6643379d46de888f2c61dcb29

scripts/__tests__/npm-utils-test.js

@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict-local
  * @format
  */
 

scripts/__tests__/scm-utils-test.js

@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict-local
  * @format
  */
 
@@ -23,7 +24,7 @@ jest
       console.log(message);
     },
     exit: exitCode => {
-      exit(exitCode);
+      process.exit(exitCode);
     },
     cp: cpMock,
   }))

scripts/releases/__tests__/__fixtures__/remove-new-arch-flags-fixture.js

@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */