Protocol Feature Study: AXI Stream transfer paradigm

[Ravencus]

Change the count of sync header 7777 to 3 instead of 4 in both tx_on_demand and rx_on_damand will result in error. This issue aims to figure out the exact data transfer paradigm (i.e. bus width, burst mode, side-channel, framing/streaming, flow control, ...) of the transfer interface.

Suggested workflow:

1. Enable side channel transfer in simulation.
2. Implement transfer with side channel in Vivado and generate bitstream.
3. Research on Framing and Streaming method, as well as their flow control.
4. Implement frame generator for data transfer.
5. Frame checking method.