Replace all non-group sockets with SocketHandler

This greatly reduces the amount of boilerplate and potential for error.

src/wine-host/bridges/vst2.h

@@ -211,12 +211,6 @@ class Vst2Bridge {
      */
     Sockets<Win32Thread> sockets;
 
-    /**
-     * A scratch buffer for sending and receiving data during `process` and
-     * `processReplacing` calls.
-     */
-    std::vector<uint8_t> process_buffer;
-
     /**
      * The MIDI events that have been received **and processed** since the last
      * call to `processReplacing()`. 99% of plugins make a copy of the MIDI