Separating the design hierarchy for multiple board support

This merge request introduces a preliminary work on support for ZCU102 board. It separates the design hierarchy into two parallel ones. This is due to the different physical interfaces of the boards. It shall allow a better readability of the structure and the code.

Main changes includes:

• Creation of different top modules for each board
• Creation of different system cores for each board
• Creation of different user cores for each board

The idea is that the top structure will be board dependent and the project implementation either board depend, or completely board agnostic with a generic architecture.