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

database/repository/repository_test.go

@@ -3,11 +3,13 @@ package repository
 import (
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"github.com/thrasher-corp/gocryptotrader/database"
 )
 
 func TestGetSQLDialect(t *testing.T) {
-	testCases := []struct {
+	for _, tc := range []struct {
 		driver         string
 		expectedReturn string
 	}{
@@ -27,22 +29,13 @@ func TestGetSQLDialect(t *testing.T) {
 			"invalid",
 			database.DBInvalidDriver,
 		},
-	}
-	for x := range testCases {
-		test := testCases[x]
-
-		t.Run(test.driver, func(t *testing.T) {
+	} {
+		t.Run(tc.driver, func(t *testing.T) {
 			cfg := &database.Config{
-				Driver: test.driver,
-			}
-			err := database.DB.SetConfig(cfg)
-			if err != nil {
-				t.Error(err)
-			}
-			ret := GetSQLDialect()
-			if ret != test.expectedReturn {
-				t.Fatalf("unexpected return: %v", ret)
+				Driver: tc.driver,
 			}
+			require.NoError(t, database.DB.SetConfig(cfg))
+			assert.Equal(t, tc.expectedReturn, GetSQLDialect())
 		})
 	}
 }