Update vscode settings to apply Prettier code formatting on Svelte files

[eumalin]

Follow up from #212

This updates vscode settings so that Prettier code formatting is applied automatically on save.

Also added a couple of recommended vscode extensions (Svelte and Prettier), so that new contributors will see what the team uses.

[carylwyatt]

These changes make sense! I pulled it down and my VS Code still won't format on save. 🤷‍♀️ I'll keep trying. I bet I have some setting from years ago that's overriding these settings.
I wonder if it would be helpful to have a formatter run in github actions? That way it won't matter if our local versions are messy, at least everything upstream will have the same formatting. What do you think, @eumalin?

[eumalin]

These changes make sense! I pulled it down and my VS Code still won't format on save. 🤷‍♀️ I'll keep trying. I bet I have some setting from years ago that's overriding these settings. I wonder if it would be helpful to have a formatter run in github actions? That way it won't matter if our local versions are messy, at least everything upstream will have the same formatting. What do you think, @eumalin?

I had the same thing happen to me. Eventually got it working when I removed "[svelte]": {} from my global user settings JSON, and reloaded the vscode window. For some reason it worked on second try.

Auto-formatting in CI gets messy, it needs write permissions and creates noisy commits that change the PR diff after the fact 😬. I'm thinking about adding Husky (pre-commit hook that formats locally), plus prettier --check in github action CI as a backstop, best of both worlds!