Add VICExvic for Vic-20 and VICExplus4 for Commodore PLUS/4 (AKA Commodore 16)

[rabbids4eva]

[Jamiras]

Please stop creating issues for adding core support to RALibretro. Unless you've personally verified that a core supports all the requirements (https://docs.retroachievements.org/libretro-core-support/), we don't need to know that we don't support it. It's not like we can make the cores compatible. We just have to wait until they are, and then we can look at adding support.