Use ModuleHandlerInterface, not ModuleHandler

Problem/Motivation

ContentNotifyManager requests \Drupal\Core\Extension\ModuleHandler as it's first construction argument.

However modules such as hook_event_dispatcher replaces the default class with \Drupal\hook_event_dispatcher\HookEventDispatcherModuleHandler.

This should not matter as both classes implement the ModuleHandlerInterface, however because ContentNotifyManager does not use the interface this breaks the site.

Steps to reproduce

Pass in any class that implements ModuleHandlerInterface that is not ModuleHandler.

Proposed resolution

Request the interface not the class.