HPCC-11506 - Alert to contain existing files

Add name(s) of files to alert user what files are the ones that currently exist.

Signed-off by: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Its in _Widget.arrayToList so your code could look something like:
var msg = this.arrayToList(arrayUtil.filter(fileList, function (file){ return item.name === file.name; }));