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

exchanges/order/order_test.go

@@ -879,9 +879,6 @@ func TestUpdateOrderFromModifyResponse(t *testing.T) {
 	od := Detail{OrderID: "1"}
 	updated := time.Now()
 
-	pair, err := currency.NewPairFromString("BTCUSD")
-	require.NoError(t, err)
-
 	om := ModifyResponse{
 		TimeInForce:     PostOnly | GoodTillTime,
 		Price:           1,
@@ -894,7 +891,7 @@ func TestUpdateOrderFromModifyResponse(t *testing.T) {
 		Status:          1,
 		AssetType:       1,
 		LastUpdated:     updated,
-		Pair:            pair,
+		Pair:            currency.NewBTCUSD(),
 	}
 
 	od.UpdateOrderFromModifyResponse(&om)
@@ -917,19 +914,16 @@ func TestUpdateOrderFromModifyResponse(t *testing.T) {
 }
 
 func TestUpdateOrderFromDetail(t *testing.T) {
-	leet := "1337"
+	t.Parallel()
 
-	updated := time.Now()
-
-	pair, err := currency.NewPairFromString("BTCUSD")
-	require.NoError(t, err)
+	var od *Detail
+	err := od.UpdateOrderFromDetail(nil)
+	require.ErrorIs(t, err, ErrOrderDetailIsNil)
 
 	id, err := uuid.NewV4()
 	require.NoError(t, err)
-
-	var od *Detail
-	err = od.UpdateOrderFromDetail(nil)
-	require.ErrorIs(t, err, ErrOrderDetailIsNil)
+	const leet = "1337"
+	updated := time.Now()
 
 	om := &Detail{
 		TimeInForce:     GoodTillCancel | PostOnly,
@@ -955,7 +949,7 @@ func TestUpdateOrderFromDetail(t *testing.T) {
 		Status:          1,
 		AssetType:       1,
 		LastUpdated:     updated,
-		Pair:            pair,
+		Pair:            currency.NewBTCUSD(),
 		Trades:          []TradeHistory{},
 	}
 
@@ -1097,10 +1091,7 @@ func TestValidationOnOrderTypes(t *testing.T) {
 	modifyOrder = new(Modify)
 	require.ErrorIs(t, modifyOrder.Validate(), ErrPairIsEmpty)
 
-	p, err := currency.NewPairFromString("BTC-USD")
-	require.NoError(t, err)
-
-	modifyOrder.Pair = p
+	modifyOrder.Pair = currency.NewBTCUSD()
 	require.ErrorIs(t, modifyOrder.Validate(), ErrAssetNotSet)
 
 	modifyOrder.AssetType = asset.Spot