Add Prettier VSCode extension

[machikoyasuda]

What this PR does

• Add the Prettier VS Code extension
• Set the Prettier extension to format on save for CSS, JS (.js, .json), but not HTML

How to test this PR

• Run this container
• Save a JS (.js, .json) file and make sure it gets formatted (Example: Use single quotes instead of double quotes on a file and make sure it does get saved)
• Save a HTML file and make sure it does not get formatted (Example: Save the alert-bar.html file and make sure it does not get reformatted)
• Save a CSS file and make sure it does get formatted (Example: Put h1, h2 on one line, and Prettier should put them on 2 separate lines)
• Test a Python file and make sure it does get properly formatted

[thekaveman]

It doesn't work on JSON files for me without this here:

"[json]": {
  "editor.formatOnSave": true,
  "editor.defaultFormatter": "esbenp.prettier-vscode"
},

Does it work for you with just the [javascript] entry?

Is there a way to specify multiple languages so we don't have to repeat the same settings for [css] etc.?

[machikoyasuda]

On the 2nd note, I tried

  "[css, javascript, json, html]": {
    "editor.formatOnSave": true,
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  },

but it doesn't work

[thekaveman]

💥 microsoft/vscode#51935 (comment)

[thekaveman]

yesterday

[machikoyasuda]

Dangggg!

[thekaveman]

Good enough for now, we'll adjust as soon as that feature lands in the next VS Code release.