[svg] Define default styling for svg icons

[nebula-aac]

There are multiple SVG icons that need some sort of styling for special cases.

This will allow ease of use when importing the SVG icons, and you don't have to style much or changes properties on the SVG icon.

There are some already done, and you can review the comments below for references.

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Contributor Guide

• 🎨 Wireframes and designs for Layer5 site in Figma (open invite)

[nebula-aac]

This is partially done here with https://github.com/layer5io/sistent/pull/34

and here with the KeppelApplicationIcon

https://github.com/layer5io/sistent/pull/34/files#diff-bb4d4146e000feb5db98b07154a82b5458f36f47c3a5ee266d6846c8da670ae3