Add directory details to the package.json of all packages (#14628)

Specifying the directory as part of the `repository` field in a `package.json`
allows third party tools to provide better support when working with monorepos.
For example, it allows them to correctly construct a commit diff for a specific
package.

This format was accepted by npm in npm/rfcs#19.

package.json

@@ -3,7 +3,11 @@
   "version": "16.7.0",
   "description": "React package for snapshot testing.",
   "main": "index.js",
-  "repository": "facebook/react",
+  "repository": {
+    "type" : "git",
+    "url" : "https://github.com/facebook/react.git",
+    "directory": "packages/react-test-renderer"
+  },
   "keywords": [
     "react",
     "react-native",