[lldb] Fix CommunicationKDP following D133251

Add `m_bytes` and `m_bytes_mutex` to `CommunicationKDP`, following refactoring
in D133251.

Differential Revision: https://reviews.llvm.org/D133365

Author: kastiglione

lldb/source/Plugins/Process/MacOSX-Kernel/CommunicationKDP.h

@@ -221,6 +221,8 @@ class CommunicationKDP : public lldb_private::Communication {
   // Classes that inherit from CommunicationKDP can see and modify these
   uint32_t m_addr_byte_size;
   lldb::ByteOrder m_byte_order;
+  std::string m_bytes;
+  std::recursive_mutex m_bytes_mutex;
   std::chrono::seconds m_packet_timeout;
   std::recursive_mutex m_sequence_mutex; // Restrict access to sending/receiving
                                          // packets to a single thread at a time