add: Ferret language icon

[itsfuad]

This pull request adds support for Ferret language and manifest file icons to the material-icon-theme. The changes include new icon definitions and mappings for Ferret-related file extensions.

Icon additions:

• Added new icons for Ferret source files (ferret.svg) and Ferret manifest files (ferret_mod.svg).

File extension mappings:

• Associated the .fer file extension with the new Ferret icon.
• Associated the fer.ret manifest file with the new Ferret manifest icon.

[itsfuad]

@MrSubidubi Could you review please!

[MrSubidubi]

Sorry for the lack of reply here. I'd very much like @PKief s opinion here (hope that is fine for you), as I think we'd probably need to add this upstream if he is fine with it.

[itsfuad]

@MrSubidubi That will be okay

[PKief]

Thanks for your contribution, really appreciate the effort here!

In general, creating a new icon upstream in material-extensions/vscode-material-icon-theme would be the preferred approach.

That said, there are a couple of constraints to keep in mind:

• The proposed icons don’t quite align with the Material Design guidelines. Typically, icons in this theme are more minimal and flat, avoid gradients, use a limited color palette, and follow the established Material icon color system.

• We try to be careful about maintaining consistency across the icon set. Adding icons that don’t follow these guidelines would make the theme less cohesive and drift away from being a true Material Icon Theme.

As an alternative, we could consider including the icons directly in this PR. However, that would require some adjustments to the upstream sync script, since it currently overwrites the existing JSON file.

Let me know what you think — happy to discuss possible approaches 👍

[itsfuad]

@PKief I agree. I would better redesign the icons which goes better with the theme. So I'm closing from here.
Thanks!