Add view-distance setter

[ImMorpheus]

Fix #1682

In stable-7 Player#getViewDistance was used on the client to get the clientside view-distance setting. In api-8 the method was moved to ServerPlayer but the setter was missing.

[ImMorpheus]

Actually, getViewDistance still refers to the client view-distance. We're hijacking CPacketClientSettings to know the client setting, since the client is telling us its view-distance.

This PR is still valid but the methods need to be renamed.

concept (ignore the names)

getClientSideViewDistance -> this is the setting on the client. The client tells us what it is and we can't change that.
getServerSideViewDistance -> server-side view-distance, enforced (the client-side view-distance is ignored if this is set) 
setServerSideViewDistance -> setter for the above