Simplify extension icon

src/vs/workbench/contrib/extensions/electron-browser/media/extensions-activity-bar.svg

 <svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg">
-<path fill-rule="evenodd" clip-rule="evenodd" d="M13.5 1.5L15 0H22.5L24 1.5V9L22.5 10.5H15L13.5 9V1.5ZM15 1.5V9H22.5V1.5H15ZM0.75 14.25L0 15V22.5L1.5 24H9L9.75 23.25L10.5 24H18L19.5 22.5V15L18 13.5H10.5V6L9 4.5H1.5L0 6V13.5L0.75 14.25ZM9 13.5V6H1.5V13.5H9ZM9 15H1.5V22.5H9V15ZM10.5 22.5H18V15H10.5V22.5Z" fill="white"/>
+<path fill-rule="evenodd" clip-rule="evenodd" d="M13.5 1.5L15 0H22.5L24 1.5V9L22.5 10.5H15L13.5 9V1.5ZM15 1.5V9H22.5V1.5H15ZM0 15V6L1.5 4.5H9L10.5 6V13.5H18L19.5 15V22.5L18 24H10.5H9H1.5L0 22.5V15ZM9 13.5V6H1.5V13.5H9ZM9 15H1.5V22.5H9V15ZM10.5 22.5H18V15H10.5V22.5Z" fill="white"/>
 </svg>