Rewrite arcade systems

[Miss-Inputs]

There should be 3 things going on here:

1. Arcade systems that are just informational, but these are also good for frontends to make collections (CPS-1, CPS-2, etc)
2. Arcade systems that have their own emulator (Naomi > Flycast, potentially ST-V, etc), and for configuration file purposes, should be a separate thing
3. Arcade systems that could have their own emulator but don't need to be a separate entry in any configuration file by default but they could be (probably like Playchoice-10 I guess)

Also arcade emulators need to be separated as such:

1. MAME, but allow for different versions, even if just one is for getting the metadata from (if the older versions can't get the metadata themselves?)
2. MAME variants like HBMAME that might have different romsets available that aren't in regular MAME, so they would need to be scanned separately
3. Other multi-machine arcade emulators (FB Neo, etc), do those have something akin to -listxml in case user doesn't use MAME?
4. Specific arcade emulators (Flycast etc) that don't do metadata, but they run the thing - although, what if someone doesn't use MAME or FB Neo or anything of the sort, and just wants to run Naomi games? Is there a way around that other than the ugly solution of having a hardcoded database of names? (Don't like that) (Though the romset name would still be lookable uppable in history.dat and such, so you could have a name from there)