Bug 34587: Abstract reports backend to allow new data types

Bug 34587: Abstract reports backend to allow new data types

Now that harvesting is possible for platforms, databases and items we need to be able to generate reports for all of these data types. Currently the reporting backend structure is very geared towards titles. Rather than copying this for each different data type, this patch abstracts the code to accept the data type as a url parameter and use that to generate a report based on a given data type

Signed-off-by: Jessica Zairo <jzairo@bywatersolutions.com>
Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>