Refactoring: more cleanup of Svg.ts, remove a few old, unused classes

src/UI/Base/Loading.svelte

@@ -2,13 +2,14 @@
   import ToSvelte from "./ToSvelte.svelte"
   import Svg from "../../Svg"
   import { twMerge } from "tailwind-merge"
+  import Loading from "../../assets/svg/Loading.svelte"
 
   export let cls: string = undefined
 </script>
 
 <div class={twMerge("flex p-1 pl-2", cls)}>
   <div class="min-w-6 h-6 w-6 shrink-0 animate-spin self-center">
-    <ToSvelte construct={Svg.loading_svg()} />
+    <Loading/>
   </div>
   <div class="ml-2">
     <slot />