JS refactors (#22227)

- Replace all default exports with named exports, except for Vue SFCs
- Remove names from Vue SFCs, they are automatically inferred from the
filename
- Misc whitespace-related tweaks

web_src/js/features/dropzone.js

@@ -1,4 +1,4 @@
-export default async function createDropzone(el, opts) {
+export async function createDropzone(el, opts) {
   const [{Dropzone}] = await Promise.all([
     import(/* webpackChunkName: "dropzone" */'dropzone'),
     import(/* webpackChunkName: "dropzone" */'dropzone/dist/dropzone.css'),