Generic component library for Editor initialization

[onsdagens]

This implements what i mentioned in #40 , and allows any crate using syncrim to implement their own component library to feed the editor.

[onsdagens]

something is broken here still

[onsdagens]

Looking better, now the editor no longer depends on a hard coded match statement to initialize placed components, allowing model crates to implement their own libraries fully.

[onsdagens]

I've implemented some RISC-V components in egui to demo the use case. The riscv/empty example provides the GUI with a library of RISC-V components so you can make your own model in the graphical editor.

[onsdagens]

All rv32i components now have properly sized egui placeholders, next goal is to implement the graphical model in the editor.