Refactor load resource and canary plugs

The purpose of this MR is to clean up all plugs that load resources.

For example we should move all custom plugs like :load_hypervisor and use :load_resource or :load_and_authorize_resource from canary. https://gitlab.com/runhyve/webapp/blob/master/lib/webapp_web/controllers/admin/hypervisor_controller.ex#L14 https://gitlab.com/runhyve/webapp/blob/master/lib/webapp_web/controllers/admin/network_controller.ex#L10