allow autocompleted in the middle of a string

[yukulele]

example:

// package.json
{
    "scripts": {
       "start": "node ./src/index.js",
       "build-css": "scss ./src/styles.scss ./dist/styles.css"
    }
}

Here ./src/index.js, ./src/styles.scss and ./dist/styles.css are not autocompleted because they are not at the start of the string.

Path should be suggested when they start the string or follow a space.