Replace NEKit dependency with reduced subset

GlassVPN/zhuhaow-NEKit/Socket/AdapterSocket/Factory/AdapterFactoryManager.swift

@@ -0,0 +1,27 @@
+import Foundation
+
+/// This is a very simple wrapper of a dict of type `[String: AdapterFactory]`.
+///
+/// Use it as a normal dict.
+public class AdapterFactoryManager {
+    private var factoryDict: [String: AdapterFactory]
+
+    public subscript(index: String) -> AdapterFactory? {
+        get {
+            if index == "direct" {
+                return DirectAdapterFactory()
+            }
+            return factoryDict[index]
+        }
+        set { factoryDict[index] = newValue }
+    }
+
+    /**
+     Initialize a new factory manager.
+
+     - parameter factoryDict: The factory dict.
+     */
+    public init(factoryDict: [String: AdapterFactory]) {
+        self.factoryDict = factoryDict
+    }
+}