Icon request: Polygon

Hello

I'd like to request a new icon named "polygon"

Additionally, there's an existing icon that is somewhat similar but represents an open or incomplete shape. Here is the image of this existing icon for reference:

No files, tests, or entry points are named. Start by reviewing the repository's existing icon assets and contribution guidance, then compare the requested Polygon image with the similar existing icon; done means a new icon named "polygon" is added in the project's supported icon outputs.

Written by the indexing model from the issue text.