addmultisigaddress creates an address respecting the setting, being unable to generate a specific type of address without also adding it to the wallet seems wrong.

I suppose in the future `addresstype` may be refactored to be wallet-specific, which would leave this non-wallet rpc call without an argument. Perhaps there should just be an optional parameter to set it.
#include <amount.h>
#include <chain.h>
#include <consensus/validation.h>
#include <core_io.h>
#include <httpserver.h>
#include <validation.h>
#include <key_io.h>
#include <net.h>
#include <outputtype.h>
#include <policy/feerate.h>
#include <policy/fees.h>
#include <policy/policy.h>
#include <policy/rbf.h>
#include <rpc/mining.h>
#include <rpc/rawtransaction.h>
#include <rpc/server.h>
#include <rpc/util.h>
#include <script/sign.h>
#include <shutdown.h>
#include <timedata.h>
#include <util.h>
#include <utilmoneystr.h>
#include <wallet/coincontrol.h>