Add import groups configuration

Summary

My actual use-case is that I want React to be imported as first but I also want line breaking between my imports. If in the importOrder configuration I setup the following : "importOrder": ["^react", "^(?!react)\\w+$"] (from https://github.com/trivago/prettier-plugin-sort-imports/issues/7#issuecomment-739413024) with importOrderSeparation: true, it will add a line break between my imports from node_modules.

Actual behavior

import React from 'react'

import classnames from 'classnames'

Expected behavior

import React from 'react'
import classnames from 'classnames'

For the moment, if you want to importOrderSeparation, there is no way of configuring import groups. I think it could be awesome if we could specify in the configuration where is the line breaking.

Possible solution

Create a configuration like:

{
  "importOrder": [
    // no line breaking if specified in a sub-array
    ["^react", "^(?!react)\\w+$"],
    "^[./]"
  ]
}

We could event remove the importOrderSeparation option because this way will allow you to put everything in the same block:

{
  "importOrder": [
    // no line breaking if specified in a sub-array
     [
       "^react", 
       "^(?!react)\\w+$", 
       "^[./]"
     ]
  ]
}

I’ll be glad to PR this 😉

Related to #1 & #7

[atombrenner]

I added PR #42 as implementation

[byara]

I have re-open #42 due to the fact that it can help a lot of people and solve lot’s of issues. Let’s work on it and improve the PR.