Returns the population type ID, defined by the below enumeration:`
cpp
enum ePopulationType
{
POPTYPE_UNKNOWN = 0,
POPTYPE_RANDOM_PERMANENT,
POPTYPE_RANDOM_PARKED,
POPTYPE_RANDOM_PATROL,
POPTYPE_RANDOM_SCENARIO,
POPTYPE_RANDOM_AMBIENT,
POPTYPE_PERMANENT,
POPTYPE_MISSION,
POPTYPE_REPLAY,
POPTYPE_CACHE,
POPTYPE_TOOL
};