Hitbtc3 new endpoints
Hitbtc3 new endpoints

Added new positions and clearing history endpoints to hitbtc3 for swaps and margin:
```
'margin/history/clearing'
'margin/history/positions'
'futures/history/clearing'
'futures/history/positions'
```

ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt