Prefixing of module names and file names

Created by: Silabs-ArjanB

In CV32E40P all module names and file names were prefixed with cv32e40p_ to avoid naming collisions at the chip level, see https://github.com/openhwgroup/cv32e40p/issues/276.

Can the same be done for all RTL files in CVA6 (I would propose a cva6_ prefix)? It would be particularly important for modules that have really generic names currently as e.g. 'alu', 'decoder'.

In CV32E40P the following naming style is used:

• Filename : cv32e40p_<something>.sv
• Module name: cv32e40p_<something>
• Instantiation: cv32e40p_<something> () <something>_i