Agent : New Step dialog (#1834)

* added file browser tree to API and dialog

* added callbacks for selected files

* added file browser to step dialog

* remove commented code

* fixed file name bug

src/sql/parts/fileBrowser/fileBrowserTreeView.ts

@@ -23,7 +23,7 @@ import { ITree } from 'vs/base/parts/tree/browser/tree';
 /**
  * Implements tree view for file browser
  */
-export class FileBrowserTreeView {
+export class FileBrowserTreeView implements IDisposable {
 	private _tree: ITree;
 	private _toDispose: IDisposable[] = [];