I'd like to propose including a configuration for Gitpod, a free online dev environment for GitHub. It allows getting started with the code base immediately. Also, it is contextual so you can for instance open pull requests with it to try the PR and even comment and approve/reject from within the IDE. I volunteer to keep the configuration updated. I created a PR so you can see the config is only a few lines long. The PR also includes a link to try it, so you can see whether you think it would be useful.
P.S.: I am working on Gitpod as well as the open-source IDE it hosts (theia-ide.org).