Add `get_idfa_status()` function
- Now it's possible to request current authorization status for the IDFA :
local status = ironsource.get_idfa_status()
-- status can be one of the following:
-- ironsource.EVENT_STATUS_AUTHORIZED
-- ironsource.EVENT_STATUS_DENIED
-- ironsource.EVENT_STATUS_NOT_DETERMINED
-- ironsource.EVENT_STATUS_RESTRICTED
-- or nil if not supported