[Glitch] Implement adding a user to a list from their profile

Port bb5558de62 to glitch-soc

app/javascript/flavours/glitch/util/async-components.js

@@ -145,3 +145,7 @@ export function EmbedModal () {
 export function GettingStartedMisc () {
   return import(/* webpackChunkName: "flavours/glitch/async/getting_started_misc" */'flavours/glitch/features/getting_started_misc');
 }
+
+export function ListAdder () {
+  return import(/* webpackChunkName: "features/glitch/async/list_adder" */'flavours/glitch/features/list_adder');
+}