Feature: Enhance the "Customize Toolbar" section by adding support for custom file extensions and folder inclusion.

### What feature or improvement do you think would benefit Files?

Current "Customize Toolbar" allows customization for specific file formats, but certain types like .exe are missing. I suggest adding the ability to input custom file extensions and allowing toolbar customization for folders as well.

### Requirements

Implement an input mechanism (e.g., a text field or tag system) that allows users to manually add file extensions (such as .exe, .py, etc.) that are not currently in the default list.

Add a dedicated "Folder" category to the customization settings, enabling a unique toolbar layout when a directory/folder is selected.

### Files Version

4.0.42.0

### Windows Version

10.0.26220.8283