Add wp-packages-update command to update WordPress packages.

This ticket exposes the packages-update script implemented at WordPress/gutenberg#19448 on WordPress core.
By running "npm run wp-packages-update" all the WordPress packages are updated to the latest version. The command is very useful when updating the Gutenberg editor core exposes.

Props isabel_brison.
Fixes #51491.

git-svn-id: https://develop.svn.wordpress.org/trunk@49129 602fd350-edb4-49c9-b593-d223f7449a82

package.json

@@ -166,6 +166,7 @@
 		"env:pull": "node ./tools/local-env/scripts/docker.js pull",
 		"test:php": "node ./tools/local-env/scripts/docker.js run --rm phpunit phpunit",
 		"test:php-composer": "node ./tools/local-env/scripts/docker.js run --rm phpunit php ./vendor/bin/phpunit",
-		"test:e2e": "node ./tests/e2e/run-tests.js"
+		"test:e2e": "node ./tests/e2e/run-tests.js",
+		"wp-packages-update": "wp-scripts packages-update"
 	}
 }