Fix: Ensure correct "upload date" for all added files

Local file storage implementation will now "touch" added files to set
modification date to current date, ensuring that files that are just
moved through a custom implementation of file object (e.g. through the
watched folder mechanism) will show with "now" as the upload date.

src/octoprint/filemanager/storage.py

@@ -455,6 +455,9 @@ def add_file(self, path, file_object, printer_profile=None, links=None, allow_ov
 
 		self._add_links(name, path, links)
 
+		# touch the file to set last access and modification time to now
+		os.utime(file_path, None)
+
 		return self.path_in_storage((path, name))
 
 	def remove_file(self, path):