Allow Renaming of Files in S3

## Problem
Currently, not able to rename the files names in S3 through VSCode's Toolkit. An option should be provided to rename any file.

## Expected behavior
User should be able to right click on the file and an option in the context menu should be shown called "Rename".
On clicking the "Rename" option a popup with an input field should be shown which will ask for NEW file name and on clicking the save button in the same popup the file/folder should be renamed.

It should handle scenarios of duplicate filenames within the same folder and provide an error if same file name already exists.

Start by locating the S3 file context-menu implementation and the existing file or folder operation used by the VS Code Toolkit. Trace how the selected S3 object is renamed or replaced, then identify the popup and error-handling tests, if present. Done means a Rename action accepts a new name and reports duplicate names in the same folder.

Written by the indexing model from the issue text.