Improve sceSystemServiceReceiveEvent stub

[StevenMiller123]

I've added both an EventType enum, and what should be the proper event struct, both based primarily off fpPS4 implementations. In the one game I've seen calling this function, the game runs a while loop until ReceiveEvent returns something other than 0, causing an infinite loop with the current implementation.

This needs testing with other games that can call this function, as I would assume some games may regress from the error return. If any regressions are found, please provide a log.

Confirmed improvements:

• Ghost of Tsushima
• Stranger of Paradise Final Fantasy Origin