Bitmart: handleMarginModeAndParams
Bitmart: handleMarginModeAndParams

Overwrite handleMarginModeAndParams to support bitmart that only has isolated margin, adjust createOrder, borrowMargin and repayMargin:

### createOrder:
```
node examples/js/cli bitmart createOrder BTC/USDT limit buy 0.00051 20000 '{"margin"
:"true"}'

bitmart.createOrder (BTC/USDT, limit, buy, 0.00051, 20000, [object Object])
2022-08-18T20:09:37.765Z iteration 0 passed in 1096 ms

{
  id: '50991813882',
  clientOrderId: undefined,
  info: { order_id: '50991813882' },
  timestamp: undefined,
  datetime: undefined,
  lastTradeTimestamp: undefined,
  symbol: 'BTC/USDT',
  type: 'limit',
  timeInForce: undefined,
  postOnly: undefined,
  side: 'buy',
  price: 20000,
  stopPrice: undefined,
  amount: 0.00051,
  cost: undefined,
  average: undefined,
  filled: undefined,
  remaining: undefined,
  status: undefined,
  fee: undefined,
  trades: [],
  fees: []
}
2022-08-18T20:09:37.765Z iteration 1 passed in 1096 ms
```

### borrowMargin:
```
bitmart.borrowMargin (USDT, 100, BTC/USDT)
2022-08-18T20:23:39.443Z iteration 0 passed in 1882 ms

{
  id: '06381584346646deb0545aa6242ec743',
  currency: 'USDT',
  amount: 100,
  symbol: 'BTC/USDT',
  timestamp: 1660854219443,
  datetime: '2022-08-18T20:23:39.443Z',
  info: { borrow_id: '06381584346646deb0545aa6242ec743' }
}
2022-08-18T20:23:39.443Z iteration 1 passed in 1882 ms
```

### repayMargin:
```
bitmart.repayMargin (USDT, 100.00229166, BTC/USDT)
2022-08-18T20:24:28.025Z iteration 0 passed in 1080 ms

{
  id: 'f8a2a63a55984a5b817c4c39681dadbc',
  currency: 'USDT',
  amount: 100.00229166,
  symbol: 'BTC/USDT',
  timestamp: 1660854268025,
  datetime: '2022-08-18T20:24:28.025Z',
  info: { repay_id: 'f8a2a63a55984a5b817c4c39681dadbc' }
}
2022-08-18T20:24:28.025Z iteration 1 passed in 1080 ms
```

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