Adding a flow runner with a GUI

[andrewdavidmackenzie]

After a few failed attempts with Gtk-rs and flutter-rust, I have decided to learn the iced GUI toolkit/library by using it on flow to create a flow runner with a GUI!

It's a binary in the flowr crate/workspace-member, in the flowr/src/bin/flowrgui directory.

This is just for the execution of flows, the idea is you can enter the flow Url, arguments and then run it and observe it executing in the GUI. It currently has standard out and image support and I am about to add stderr, stdin, and file reading/writing.

I have a working first version (see some screen shots in the README) that I was very pleased to get working!

I haven't spent much time on design/styling, that is time consuming and not a strength of mine, maybe someone will help there!?

Later, I would like to create the flow "designer" or "IDE" for writing flows visually. That will be another big chunk of work, so let's see when I can get to it.