Move z-index values to separate file

src/components/browser-modal/browser-modal.css

src/components/cards/card.css

src/components/coming-soon/coming-soon.css

src/components/context-menu/context-menu.css

src/components/drag-layer/drag-layer.css

src/components/gui/gui.css

src/components/import-modal/import-modal.css

src/components/loader/loader.css

src/components/menu-bar/menu-bar.css

src/components/modal/modal.css

src/components/monitor/monitor.css

src/components/preview-modal/preview-modal.css

src/components/stage-header/stage-header.css

src/components/stage/stage.css

src/components/webgl-modal/webgl-modal.css

src/css/z-index.css