[ICON REQUEST]: linux-flat

### I have searched through the issues and didn't find my problem.

- [X] Confirm

### About the icon

Unshaded version of linux-original to reduce size

### Links and sources

https://commons.wikimedia.org/wiki/File:Tux-flat.svg

### Additional information

Currently there are linux-original and linux-plain. I would like a colored variant, however, the original variant is a whole 190KiB in size. This is by far the largest out of a few dozen icons I am using otherwise. It is bigger than the whole fontawesome-solid icon font and 40% of the devicon icon font with all plain logos.

Compare the existing linux-original and linux-plain icons, then review the linked Tux-flat.svg source. Identify how the repository stores and generates icon assets, and add a colored, unshaded linux-flat variant with a substantially smaller size than linux-original. Done means the new icon is available alongside the existing Linux variants.

Written by the indexing model from the issue text.