T&A: Refactor ilTestTopList according to data table component

[lukas-heinrich]

Refactors ilTestTopListTable by using the DataTable component instead of ilTable2GUI inheritance. Removes unnecessary code and adjusts the unit tests:

• Outsources database query to new repository class and use a generator instead of returning the complete array
• Creates a new Table class that implements the creation and formatting of columns and rows
• Adapts unit tests to the new structure and creates test case for formatting the time span
• Streamlines the code by passing queries with parameters for sorting and display type to general functions