404 on uninstall flow

Problem/Motivation

There is a improvement that we can do on uninstall because the normal flow there is an error.

Steps to reproduce

1. Install the empty_front_page drush en empty_front_page -y
2. Open the page /admin/config/system/site-information, and see the front-page to /empty-front-page
3. Open the front page and you'll see that is a empty front-page
4. Uninstall the empty_front_page drush pmu empty_front_page -y
5. Go to the page /admin/config/system/site-information, and see the front-page still there /empty-front-page
6. Open the front page

Result: You'll see the 404 page not found

Expected: The home should back to the original state when Drupal is installed

Proposed resolution

Implements hook_uninstall to apply the logic when is uninstalled back the value to empty as the default when the Drupal is installed

Remaining tasks

User interface changes

API changes

Data model changes