exchanges: shift GetDefaultConfig wrapper function to exchange.go (#1472)

* Shift wrapper function GetDefaultConfig to exchange.Base method definition, to ensure set defaults doesn't get called twice and to reduce code

* rm alphapoint bootstrap method as is defined as exchange.Base method

* add tests

* glorious: make it a function and make it IBOTEXCHANGE

---------

Co-authored-by: shazbert <ryan.oharareid@thrasher.io>

engine/withdraw_manager_test.go

@@ -24,8 +24,7 @@ func withdrawManagerTestHelper(t *testing.T) (*ExchangeManager, *portfolioManage
 	t.Helper()
 	em := NewExchangeManager()
 	b := new(okx.Okx)
-	b.SetDefaults()
-	cfg, err := b.GetDefaultConfig(context.Background())
+	cfg, err := exchange.GetDefaultConfig(context.Background(), b)
 	if err != nil {
 		t.Fatal(err)
 	}