Migrate DownloadFileshareArtifactsV0 task to Node10 (#15840)

Author: Ivan Golubev

Tasks/DownloadFileshareArtifactsV0/Tests/L0.ts

@@ -9,7 +9,7 @@ describe('DownloadFileshareArtifactsV0 Suite', function () {
     after(() => {
     });
 
-    it('Does a basic hello world test', function(done: MochaDone) {
+    it('Does a basic hello world test', function(done: Mocha.Done) {
         // TODO - add real tests
         done();
     });