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/components/ActivityHeatmap.vue

@@ -18,7 +18,6 @@
 import {CalendarHeatmap} from 'vue3-calendar-heatmap';
 
 export default {
-  name: 'ActivityHeatmap',
   components: {CalendarHeatmap},
   props: {
     values: {