codebase: Cleanup various things (#1935)

* codebase: Rid base64/hex to string common funcs

* codebase: Rid local scope variable usage and other improvements

* codebase: Refactor currency pair usage across multiple exchanges

- Updated HitBTC tests to use the new currency pair format.
- Modified Kraken futures types to use currency.Pair instead of string for Symbol.
- Adjusted Kraken wrapper methods to handle currency pairs correctly.
- Refined OKX tests and types to utilize currency.Pair for instrument IDs.
- Enhanced Poloniex tests to consistently use predefined currency pairs.
- Streamlined order and orderbook tests to replace string pairs with currency.NewBTCUSD().
- Improved Yobit tests to utilize a standardized currency pair format.
- Updated validator wrapper to use currency pairs directly instead of string conversions.

* codebase: Use types.Number where possible

* refactor: update PayoutFee type to types.Number for consistency

* Refactor: Remove crypto functions to use standard library and other minor changes

- Removed custom crypto functions for SHA256, SHA512, and MD5 from the common/crypto package.
- Replaced usages of removed functions with standard library implementations in various files including:
  - cmd/websocket_client/main.go
  - engine/apiserver.go
  - exchanges/kraken/kraken.go
  - exchanges/lbank/lbank.go
  - exchanges/okx/okx_business_websocket.go
  - exchanges/kucoin/kucoin_websocket.go
  - gctscript/vm/vm.go
- Updated tests to reflect changes in the crypto functions.
- Renamed several functions for clarity, particularly in the context of order book updates across multiple exchanges.

* refactor: replace assert with require for consistency in test assertions

* refactor: Improve Binance futures candlestick test, standardise orderbook update function names and improve test parallelism

* refactor: Replace require.Len with require.Equal for better output in TestGetFuturesKlineData

gctscript/wrappers/validator/validator.go

@@ -116,16 +116,11 @@ func (w Wrapper) QueryOrder(_ context.Context, exch, _ string, _ currency.Pair,
 		return nil, errTestFailed
 	}
 
-	pair, err := currency.NewPairFromString("BTCAUD")
-	if err != nil {
-		return nil, err
-	}
-
 	return &order.Detail{
 		Exchange:        exch,
 		AccountID:       "hello",
 		OrderID:         "1",
-		Pair:            pair,
+		Pair:            currency.NewBTCUSD(),
 		Side:            order.Ask,
 		Type:            order.Limit,
 		Date:            time.Now(),

gctscript/wrappers/validator/validator_test.go

@@ -28,8 +28,8 @@ const (
 )
 
 var (
-	currencyPair, _ = currency.NewPairFromString("BTCAUD")
-	testWrapper     = Wrapper{}
+	currencyPair = currency.NewPair(currency.BTC, currency.AUD)
+	testWrapper  = Wrapper{}
 )
 
 func TestWrapper_Exchanges(t *testing.T) {