BREAKING CHANGE:
- `file-icon` for the configurations is removed
- Configuration objects `icon` option changed and is now working differently: you can either use a material icon code or a custom image (see Public static files in the UI Plugin docs).
- Task objects have a new `icon` option wich works exactly the same
- By default, if no icon is provided for either the config or the task, the corresponding vue-cli plugin logo will be used instead (if any).