优化内容压缩

* 取消用户设置的压缩级别，现在压缩级别通过系统自动设置
* Pool中的对象命中100万次时自动销毁，避免内存泄漏
* 降低Pool中的对象数量，避免占用太多内存
* 根据系统CPU线程数自动计算压缩级别，避免消耗太多CPU
* zstd限制解码的最大Window
* zstd使用低内存模式

internal/compressions/utils_test.go

@@ -0,0 +1,27 @@
+// Copyright 2024 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .
+
+package compressions_test
+
+import (
+	"github.com/TeaOSLab/EdgeNode/internal/compressions"
+	"github.com/iwind/TeaGo/assert"
+	"testing"
+)
+
+func TestGenerateCompressLevel(t *testing.T) {
+	var a = assert.NewAssertion(t)
+
+	t.Log(compressions.GenerateCompressLevel(0, 10))
+	t.Log(compressions.GenerateCompressLevel(1, 10))
+	t.Log(compressions.GenerateCompressLevel(1, 4))
+
+	{
+		var level = compressions.GenerateCompressLevel(1, 2)
+		t.Log(level)
+		a.IsTrue(level >= 1 && level <= 2)
+	}
+}
+
+func TestCalculatePoolSize(t *testing.T) {
+	t.Log(compressions.CalculatePoolSize())
+}