Merge `CVA6Cfg` and `ArianeCfg`

Created by: zarubaf

This commit merges these two similar strategies for parameterization. A further step towards the clean-up. @Jbalkind I haven't adapted the OpenPiton wrapper so that will break for sure. Not sure how you'd like to proceed but probably it makes the most sense to adapt that once and for all, instead of incremental. Also see the new enum type, I also have removed SwapEndianess since I haven't seen a use-case for that anymore (it was set to 1 in the OP config). I might have missed the underlying nature, so please do let me know.

How has that been tested?

Running dhrystone before and after the merge.

Fixes #1319 (closed)