Get memory usage of current running SrCDS server.

Requires SourceMod.

Most of this code from Kxnrl#0001, in the AlliedModders discord, here: https://canary.discord.com/channels/335290997317697536/335290997317697536/856238249457614858 .

This extension has been wholly refactored, thanks to krxnl for giving me a good starting point.

Native provided as Native int GetMem(), returning mem usage in KB. With the plugin provided, use sm_getmem.

sm_cleanmem - Run some memory cleaning commands (I recommend putting this in a server config / running it on map change)

sm_getmem && sm_getmem_mb - Get current used mem of running server