Enforce that CANMessage.m_dataSize won't be larger than 8 bytes

[NoahAndrews]

Previously, the actual data array in CANMessage was always limited to 8 bytes, but m_dataSize could be larger than that, which could trick consumers of this library into reading from an invalid memory location.

Marking this as a draft*, because I think CandleWinUsbDeviceThread suffers from a similar issue. The data field on candle_frame_t (which represents the actual format of the USB packet) always has a length of 8, but it's possible for the dlc sent over CAN to be higher than that. This line of code should not assume that frame.data is at least as large as frame.can_dlc:

CANBridge/src/main/native/include/rev/Drivers/CandleWinUSB/CandleWinUSBDeviceThread.h

Line 189 in 8d0f4f6

memcpy(frame.data, el.m_msg.GetData(), frame.can_dlc);

We should also determine whether gs_usb devices populate frame.can_dlc values larger than 8 as their over-the-CAN-bus format of 4 bits, or whether they handle expanding that to the actual size (DLC values ranging from 1001 to 1111 are used to specify data lengths of 12, 16, 20, 24, 32, 48, and 64 bytes, respectively), as that will influence that logic.

*also, it doesn't currently compile