* Move userId in API from route to optional query parameter
* Standardize UserViewsController
* Move userId to query in ImageController
* Move userId to query in ItemsController
* Move userId to query in PlaystateController
* Move userId to query in SuggestionsController
* Move userId from route to query in UserLibraryController
* Clean up routes
* Move userId to query in UserController
* fix bad merge
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Co-authored-by: Niels van Velzen <git@ndat.nl>
* Use Guid.Equals(Guid) instead of the == override
* Ban the usage of Guid.Equals(Object) to prevent accidental boxing
* Compare to default(Guid) instead of Guid.Empty