Enhance New+ Feature to Work when Right Clicking on Files as well

### Description of the new feature / enhancement

At present, the New+ feature works when right‑clicking on a folder, but it does not respond when right‑clicking on a file.
I suggest enhancing it so that:
Right‑clicking on a file also triggers the New+ action.
The newly created file or folder to be placed in the same directory as the file that was clicked.

### Scenario when this would be used?

Sometimes search results show only files and no folders. In such cases, it would be useful if we could add a note directly into the same folder as a particular file we see on the search result.

### Supporting information

_No response_

Start by locating the existing New+ implementation and the right-click handling for folders in PowerToys. Trace how the target directory is selected, then check the relevant tests or manual verification path to confirm that right-clicking a file creates the item beside that file while folder behavior remains unchanged.

Written by the indexing model from the issue text.