This PR adds file associations for stylelint files.

This is how it looks like in Zed (the icon doesn't exist):
![default javascript file icon is shown for
stylelint.config.js](https://github.com/user-attachments/assets/a873d7fc-1b8a-4a9c-8e92-1be56d5b01b1)

In a dev version of an icon theme it looks like this (icon sourced from:
https://github.com/vscode-icons/vscode-icons/blob/master/icons/file_type_stylelint.svg
):
![stylelint file icon is shown for
stylelint.config.js](https://github.com/user-attachments/assets/ddbb068d-7986-43de-94f8-9c844cb6b96f)

Release Notes:

- Icon themes: Added Stylelint file icon associations.

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Co-authored-by: Marshall Bowers <git@maxdeviant.com>