📋 Description

Following up from #2697 (comment).

I would like to make life easier for potential new shields.io contributors by implementing gitpod.io support for Shields development. Disclaimer: I work on Gitpod.

This could provide newcomers (and also Shields maintainers) with pre-configured workspaces in the cloud, allowing them to get started instantly, without having to first set up a complete development environment themselves.

TODO:

• Allow cloning any Shields branch or pull request in Gitpod
• Automatically pre-run npm install
• Automatically start the Shields server and open it in a live preview
  • (Doesn't work yet, because the badge server on port 8080 refuses any requests with non-localhost domains, which Gitpod's preview pane tries to do) fixed in Fix overriding bind address on CLI #2773
  • add onOpen: open-preview to port 8080 in .gitpod.yml in order to auto-open preview when the Shields server starts (but maybe wait for [mini-browser] Make the mini-browser background white again eclipse-theia/theia#4096 to restore the white background in Gitpod's preview)
• Pre-install ImageMagick (maybe not useful)
• Mention experimental Gitpod support in README.md to help newcomers get started (done in Make code contributions easier with Gitpod #2783)
• Enable pre-built branches & pull requests once Gitpod supports those (so that contributors & reviewers don't have to wait for npm install && npm run build to finish before getting started)
• Auto-format on Save with Prettier (see [editor] Format the text on saved. eclipse-theia/theia#3338)
• Suggest useful Shields workflows & commands (once [tasks] Support VS Code task definitions gitpod-io/gitpod#247 is implemented)

Please let me know what you think of this idea, and if you know other setup/configuration things that should be automated for new contributors.