Add support for file-loader 3.x

[hpohlmeyer]

• Operating System: MacOS 10.14.2
• Node Version: 11.4.0
• NPM Version: 6.4.1
• webpack Version: 4.28.1
• less-loader Version: 4.1.0

This issue is for a:

• bug
• feature request
• modification request

Code

Webpack config

The styles.less file, that throws the error:

@import './fonts';

/** Import CSS for custom components, that are not part of the ui library. */
@import './custom/code-block';
@import './custom/http-operation-badge';

Expected Behavior

Should compile without errors.

Actual Behavior

Breaks with

ERROR in ./src/styles/styles.less (./node_modules/css-loader/dist/cjs.js!./node_modules/less-loader/dist/cjs.js!./src/styles/styles.less)
Module not found: Error: Can't resolve 'url-loader' in '/absolute/path/to/project'

I suppose this is caused by the removal of file-loaders useRelativePath-option in version 3.0.0.

@jhnns said that the less-loader usually applies the relativePath-option automatically, which sound like a problem, if the option is not supported anymore.

How Do We Reproduce?

Use less-loader with file-loader 3.x

[alexander-akait]

Not related to less-loader, you need install url-loader