Fix setting CVAR_VM_CREATED flag on user created cvars

Fix setting CVAR_VM_CREATED flag on cvars created using set[asu] commands (including archived cvars from cfg) and trap_Cvar_Set.

trap_Cvar_Register called Cvar_Get which cleared CVAR_USER_CREATED flag, but CVAR_VM_CREATED wasn't set because the cvar already existed.