Configure GitHub Codespace

[janosh]

This PR makes the example apps table in the readme more useful. Before we only had links to the app scripts. This PR adds a "Launch Codespace" button next to each example which opens the CT repo in a GitHub Codespace and auto-installs it along with deps. The goal is to make it easier for beginners to start using CT by automating the setup as much as possible. Ideally they have to click a link from the readme, wait for the Codespace to spin up and then invoke a python command to launch the example app of their choosing (with hot reloading of code changes btw, making it a nice playground to start tinkering).

Just tried it out and seems to be working! I assume this was made easier by @tschaume's setup refactoring in #292 so thanks for that. 👍

Here's the basic_hello_world.py example app running in a browser inside a codespace running in the browser... Let the web inception begin. 😄

Readme examples table

[janosh]

@mkhorton In case you give this a try, would be curious to hear if it works for you. I was getting some errors from the structure examples but I think they were actual CT errors (StructureGraph missing method get_scene()), not due to the Codespace config.

[janosh]

Dropping dscribe from optional deps set 'server' since it hasn't been an essential dep since #270 and was causing pip install .[server] to fail, leading to non-functional codespaces.

[mkhorton]

@janosh this is a great idea, works wonderfully in Chrome :)

Some terminal output not displayed in Safari which leads to unexpected behaviour, but I assume this is not our issue. There's a delay in the dependencies being installed and available when launching the Codespace which wasn't immediately obvious. Overall really nice for demos however, I can definitely see myself recommending this to others!

The earlier error you saw was due to a refactor last week, that was now fixed in #296