message: Allow copy of `IRCode` with editable CFG
  Summary: Extend `IRCode::IRCode(const IRCode&)` to allow a copy of code that has an editable CFG built (the `IRList` is empty).
diff: @@ -584,8 +584,14 @@ IRCode::IRCode(DexMethod* method, size_t temp_regs) : m_ir_list(new IRList()) {
  }
  IRCode::IRCode(const IRCode& code) {
  + if (code.editable_cfg_built()) {
  + m_ir_list = new IRList(); // Empty.
  + m_cfg = std::make_unique<cfg::ControlFlowGraph>();
  + code.m_cfg->deep_copy(m_cfg.get());
  + } else {
  IRList* old_ir_list = code.m_ir_list;
  m_ir_list = deep_copy_ir_list(old_ir_list);
  + }
  m_registers_size = code.m_registers_size;
  if (code.m_dbg) {
  m_dbg = std::make_unique<DexDebugItem>(*code.m_dbg);
  