[Feature Request] Add an apio command to generate the design graph.

[zapta]

This proposal is for a new command such as apio graph or apio show that uses the yosys's show capability and generates a file hardware.svg with a diagram of the design.

For example, the following yosys command

yosys -q -p "show -format svg -colors 1 -prefix hardware main" deserializer.v leds.v main.v queue.v queue_pusher.v reset_gen.v sensor_timing.v serial_tx.v

Generated for me this graph

Open points

• The command requires the grpahviz binaries, so these can be installed by apio (preffered), and independent by the user.
• The generated diagram can be too detailed and busy. I filed a request for a simplified diagram but do not know if/when it will be available. https://github.com/YosysHQ/yosys/issues/4236

[zapta]

The api graph command was added, so closing this issue.

Future improvements may include auto launch of a .svg viewer or a more readable graph.