Per feedback in T180021 there should be a user setting to disable/enable Wikispeech.
Together with the user config we also need a global config for whether Wikispeech is enabled globally. [Or better a list of which user groups its enabled for]
This is also a good opportunity to add functionality for disabling Wikispeech when we are not in read mode (try Wikispeech in the history tab for a motivation). In the future we might want to read this content in some other way but for now disabling it is probably best.