Add option to also generate type-per-line

[bartveneman]

For syntax highlighting purposes in a diff I want to know what sort of thing we're rendering in each line. So apart from returning the CSS as a string I also want an array if types:

import { format_with_types ] from '@projectwallace/format-css'

let { css, types } = format_with_types('a { color: red; }')

// => css
`a {
  color: red;
}`

// => types
[
  1, // selector
  2, // declaration
  3, // bracket
]

The following types are needed:

• selector (a)
• declaration (color: red;)
• bracket ({, })
• atrule (@media all)

This is sufficient for highlighting purposes because the formatting rules dictate that every atrule or selector prelude line end with a { and every declaration ends with a ;.

We don't need to support this for minified CSS because that's just madness.

[bartveneman]

Thinking out loud:

could it also be enough to check if:

• line starts with @ and ends with { => atrule
• line ends with , or { => selector
• line ends with ; => declaration
• line ends with } => bracket
• empty line => whatev