web: fix event propagation in search-select wrappers (#8224)

web: fix event propogation in search-select wrappers

Two different patches, an older one that extracted long search
blocks that were cut-and-pasted into a standalone component, and a
newer one that fixed displaying placeholder values properly,
conflicted and broke a relationship that allowed for the values to
be propagated through those standalone components correctly.

This restores the event handling and updates the listener set-ups
with more idiomatic hooks into Lit's event system.

web/src/elements/forms/SearchSelect/ak-search-select.ts

@@ -220,6 +220,7 @@ export class SearchSelect<T> extends CustomEmitterElement(AKElement) {
     onMenuItemClick(obj: T | undefined) {
         return () => {
             this.selectedObject = obj;
+            this.dispatchCustomEvent("ak-change", { value: this.selectedObject });
             this.open = false;
         };
     }