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/mock/recording.go

@@ -1,6 +1,7 @@
 package mock
 
 import (
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"io"
@@ -14,7 +15,6 @@ import (
 	"sync"
 
 	"github.com/thrasher-corp/gocryptotrader/common"
-	"github.com/thrasher-corp/gocryptotrader/common/crypto"
 	"github.com/thrasher-corp/gocryptotrader/common/file"
 	"github.com/thrasher-corp/gocryptotrader/encoding/json"
 )
@@ -115,7 +115,7 @@ func HTTPRecord(res *http.Response, service string, respContents []byte) error {
 
 	case textPlain:
 		payload := res.Request.Header.Get("X-Gemini-Payload")
-		j, dErr := crypto.Base64Decode(payload)
+		j, dErr := base64.StdEncoding.DecodeString(payload)
 		if dErr != nil {
 			return dErr
 		}

exchanges/mock/server.go

@@ -1,6 +1,7 @@
 package mock
 
 import (
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"io"
@@ -14,7 +15,6 @@ import (
 	"strings"
 
 	"github.com/thrasher-corp/gocryptotrader/common"
-	"github.com/thrasher-corp/gocryptotrader/common/crypto"
 	"github.com/thrasher-corp/gocryptotrader/common/file"
 	"github.com/thrasher-corp/gocryptotrader/encoding/json"
 )
@@ -179,9 +179,7 @@ func RegisterHandler(pattern string, mock map[string][]HTTPResponse, mux *http.S
 					log.Fatal("Mock Test Failure - Cannot find header in request")
 				}
 
-				base64data := strings.Join(headerData, "")
-
-				jsonThings, err := crypto.Base64Decode(base64data)
+				jsonThings, err := base64.StdEncoding.DecodeString(strings.Join(headerData, ""))
 				if err != nil {
 					log.Fatal("Mock Test Failure - ", err)
 				}