fix variable length warning using std::vector

[ijnek]

Resolves: https://github.com/ROBOTIS-GIT/DynamixelSDK/issues/553

Gets rid of the following warning:

Starting >>> dynamixel_workbench_toolbox
--- stderr: dynamixel_workbench_toolbox                              
/home/ijnek/tmp_workspaces/dynamixel_control_ws/src/dynamixel-workbench/dynamixel_workbench_toolbox/src/dynamixel_workbench_toolbox/dynamixel_driver.cpp: In member function ‘bool DynamixelDriver::readRegister(uint8_t, uint16_t, uint16_t, uint32_t*, const char**)’:
/home/ijnek/tmp_workspaces/dynamixel_control_ws/src/dynamixel-workbench/dynamixel_workbench_toolbox/src/dynamixel_workbench_toolbox/dynamixel_driver.cpp:776:11: warning: ISO C++ forbids variable length array ‘data_read’ [-Wvla]
  776 |   uint8_t data_read[length];
      |           ^~~~~~~~~
/home/ijnek/tmp_workspaces/dynamixel_control_ws/src/dynamixel-workbench/dynamixel_workbench_toolbox/src/dynamixel_workbench_toolbox/dynamixel_driver.cpp: In member function ‘bool DynamixelDriver::syncWrite(uint8_t, uint8_t*, uint8_t, int32_t*, uint8_t, const char**)’:
/home/ijnek/tmp_workspaces/dynamixel_control_ws/src/dynamixel-workbench/dynamixel_workbench_toolbox/src/dynamixel_workbench_toolbox/dynamixel_driver.cpp:1012:11: warning: ISO C++ forbids variable length array ‘multi_parameter’ [-Wvla]
 1012 |   uint8_t multi_parameter[4*data_num_for_each_id];
      |           ^~~~~~~~~~~~~~~
---

[sven-hoek]

Haven't checked this out to build and test it but seems to be exactly what I did and it worked for me. Thanks for making a pull request (btw, you could have committed these changes onto the branch of the other PR you made and wouldn't have needed to delete it, but this way it's also fine) Also: the #include <memory> isn't necessary here anymore but a #include <vector> instead (or rather best/good practice than necessary).

[ijnek]

Oops, accidentally closed as a result of a branch rename. As Github doesn't let me re-open this PR, I'm going to open another one (#364)