File Management - upload

Is it available to show whether "**overwrite**" the file existed or "**skip**" when we try to upload files? This little window can largely protect us from uploading files to wrong paths (without noticing it).

The issue does not name a file, test, or upload entry point. Trace the file-management upload flow first and determine where the application can detect an existing destination; done means showing whether the operation will overwrite or skip the existing file before uploading.

Written by the indexing model from the issue text.