Add extended GUI tutorial

[banchan86]

As mentioned during the Bonsai Dev Conference the current documentation is a bit barebones. For the manual section, since the operators are kind of straight forward, there might not be a need for further documentation other than having screenshots/gifs of the GUI elements and some more explanation of the container controls. Having some tutorials/examples with videos though would really help illustrate the power of the package. I plan to go through the video recordings and package demos to see what can be added.

[banchan86]

After gaining some experience with the Bonsai.GUI I now have a better idea about how to expand the documentation and a step by step tutorial on building a typical neuroscience experimental GUI would be a perfect fit. This would include:

• textbox for inputting experiment or animal ID and linking it to files that need to be renamed (CsvWriter/VideoWriter)
• button to run the experiment or multiple animals
• mashups for simple video composition (like overlaying point tracking)
• arranging and adjusting layouts
• Optional: adjusting experimental parameters
• Optional: graph controls

Some references:
https://github.com/orgs/bonsai-rx/discussions/1569
https://github.com/orgs/bonsai-rx/discussions/2115

I will get started working on a draft.