rpc: Add rpc_getUserAccountId, rpc_getAccountUserId, rpc_getAvatarUserId, and rpc_getAvatarAccountId
rpc: Add rpc_getUserAccountId, rpc_getAccountUserId, rpc_getAvatarUserId, and rpc_getAvatarAccountId

These four methods form the base of our ID translations.

Spiderlover/Toontown,Spiderlover/Toontown