The current logic for showing discussion providers makes it hard to switch from the legacy to the new provider. This commit changes the conditions in which different providers are shown, and which provider is used as default. Before this commit, the new provider would be hidden if the legacy provider was in use and vice-versa. So both would only be shown if neither legacy nor the new provider were in use (i.e. an LTI provider was in use). Now, all providers are always displayed to global staff. If the waffle flag for the new provider is set (`discussions.enable_new_structure_discussions`), then new provider is always displayed, and the legacy provider is hidden unless it's currently in use. If flag is not set, then the new provider is always hidden unless it is used by a course. Finally, the default provider now depends on the flag above. If it is set globally, then the default provider is the new provider, otherwise the legacy provider remains the default provider.
LMS (Learning Management System) -------------------------------- This directory contains code relating to the student portal for edX.