Handle HTTP request to view recently items

[EmadAghaei]

Users may make an HTTP request to view the list of items that they have previously viewed. This handler searches the items log of all users and returns the items viewed by the user (which has the viewed flag set). If there are no such items, it returns an empty collection. The handler may make use of a 3rd party persistence library. Finally, the handler should check the validity of the input arguments. If any of the input arguments are empty or null, a 400 response should be returned with a description.

Important notes. The endpoint address should be "/recentlyViewedItems". The URL query parameter is "userId".