Attempt 2 at a geyser fix, different way

This reverts the previous fix, Packet Events no longer required. This adds a new placeholder - %simplenicks_nickname% which should fix the issue, as it does not rely on the display name API. Also adds a Cache so that Placeholder API is not constantly reading from the YML

There are known issues with the /nick save command in this version, will be fixed on the next major release