Make return value for create/update API calls more consistent

[tw4l]

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In some resource creation API endpoints we return the id for the object created, in others we don't. This could use a consistency pass.

@SuaYoo suggested returning the entire created object under a data key, which seems like a good idea to me!

@emma-sg suggested doing the same for PATCH requests so that we don't need to make follow-up requests from the frontend