plugins.registerHook removed, use plugins.hooks.register
plugins.unregisterHook removed, use plugins.hooks.unregister
plugins.fireHook removed, use plugins.hooks.fire
plugins.hasListeners removed, used plugins.hooks.hasListeners
https://github.com/NodeBB/NodeBB/commit/dd4e66e22c93586d389b47fa197154620508ae8f#diff-b4eb852db38c86236f6d2c1b7fcfc03c1b93a090a534361b9c21e790620fce39