[Quest]: Improve editing experience

[NullVoxPopuli]

• lint in the browser ember-template-lint/ember-template-lint#2120
• contextual errors from the VM (line them up in the editor, rather than render them in a corner of the window)
• be able to capture and intercept VM crashes that currently cause the app to refresh+redirect
  • Write RFC for Error Boundaries? discuss with @chancancode and @wycats ? Due to the new iframe-based rendering approach, this is not needed
    • It's been asked for: emberjs/rfcs#513
  • Re-implement an ember-app in ESM for the iframe part
    • https://github.com/lifeart/demo-ember-vite
    • https://github.com/NullVoxPopuli/polaris-starter
    • Only v2 addons would be supported. For the styleguide use case, the design system libraries must be open source, so that CDNs can be used to fetch the assets (web container has too slow of a boot time)
• add inline "hints" to the editor(s) so that it's clear if the cursor is in markdown mode or ember mode
• add completion APIs
  • for Monaco: lifeart/ember-language-server#305
  • investigate if CodeMirror supports LSP it does
• Decide on CodeMirror vs Monaco CodeMirror - more accessible. Will be more work since it's newer / less support, but accessibility is important.
• determine if a pre-configured editor for ember can/should be pre-packaged and shipped as an addon
  • this app then almost becomes solely the combination of 2 addons + some layout
• CodeMirror specific improvements
  • Finish NullVoxPopuli/glimdown#2
    • Write Glimmer Language
      • Auto-indentation on new line
      • Highlighting
      • Intellisense / scope
    • Write GJS/GTS Language
    • Write Glimdown Language
      • GJS/GTS will be via tagged code fences

[NullVoxPopuli]

Multi-file editing? https://www.sveltelab.dev/
This uses full web-containers which requires installing dependencies 🤔
Might be good to fork for ember later on