feat: add folder icons for freebsd, netbsd and puredarwin

[Murateba]

Description

Add new folder icons

• folder-freebsd.svg for freebsd, bsd
• folder-netbsd.svg for netbsd
• folder-darwin.svg for puredarwin, darwin

Contribution Guidelines

• By creating this pull request, I acknowledge that I have read the Contribution Guidelines for this project
• I have read the Code Of Conduct and promise to abide by these rules

[github-actions]

Preview

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[lucas-labs]

Thanks for the PR!

Just a small note: This icon pack usually prefer a 2 colors scheme for folder icons.

Where the motive and the background colors are chosen fom the following rows:

Expand Palette

From https://pkief.github.io/material-color-converter/

I can see you're using colors from the last row (I think). This makes the icon looks ok in most light themes, but it can make it impossible to see in some dark themes.

Imagine someone uses this theme (I know, I know, but let's suppose for a second that such a person exists):

The freebds icon wouldn't work at all there. That's why we use half-toned colors. They usually work fine in virtually all themes, dark and light.

You can read more here