Issue #3273364 by tedbow: Implement Extension Updater logic

..._updates_extensions/automatic_updates_extensions.info.yml

automatic_updates_extensions/src/ExtensionUpdater.php

...updates_extensions/tests/fixtures/fake-site/composer.json

...updates_extensions/tests/fixtures/fake-site/composer.lock

...s/tests/fixtures/fake-site/vendor/composer/installed.json

...s_test_api/automatic_updates_extensions_test_api.info.yml

...est_api/automatic_updates_extensions_test_api.routing.yml

...tomatic_updates_extensions_test_api/src/ApiController.php

...c_updates_extensions/tests/src/Build/ModuleUpdateTest.php

...ates_extensions/tests/src/Kernel/ExtensionUpdaterTest.php