Add support for selecting folders in file dialog

[Anders Evenrud]

As of now you can only select files in the "file" dialog. Needs to support an option for this.

[Anders Evenrud]

@hanswurmwurst I have now added support for selecting directories :)

core.make('osjs/dialog', 'file', {
  filetype: 'directory' // New option
}, (button, file) => {
});

[Anders Evenrud]

npm update @osjs/dialogs