Hitbtc3: fetchPositions, handleMarginModeAndParams
Hitbtc3: fetchPositions, handleMarginModeAndParams

### fetchPositions:
```
node examples/js/cli hitbtc3 fetchPositions BTC/USDT '{"margin":true}'

hitbtc3.fetchPositions (BTC/USDT, [object Object])
2022-08-27T05:54:19.673Z iteration 0 passed in 188 ms

  symbol | notional | marginMode | marginType | liquidationPrice | entryPrice | unrealizedPnl | percentage | contracts | contractSize | markPrice | side |
hedged |     timestamp |                 datetime | maintenanceMargin | maintenanceMarginPercentage |    collateral | initialMargin | initialMarginPercentage | leverage | marginRatio
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BTC/USDT |          |   isolated |   isolated |                0 |   20097.46 |               |            |   0.00087 |              |           |      |
       | 1661579608226 | 2022-08-27T05:53:28.226Z |                   |                             | 25.2562880245 |               |
   |       12 |
1 objects
2022-08-27T05:54:19.673Z iteration 1 passed in 188 ms
```

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