web: improve testability (#6952)

web/improve testability

This is a trio of small hacks that allow the E2E tests to find several components
on the page while the test is running:

- Add a `data-managed-for` field to SearchSelect's positioned elements. If a search
  has a `name` field, it will be reflected here, allowing tests to find specific
  instances of the dropdown elements.
- Add a forwarder to the search select wrappers we use for our SearchSelect.
- Added aria details to the UserLibrary header to make it easy to identify.

web/src/admin/common/ak-flow-search/FlowSearch.ts

@@ -122,6 +122,7 @@ export class FlowSearch<T extends Flow> extends CustomListenerElement(AKElement)
                 .renderElement=${renderElement}
                 .renderDescription=${renderDescription}
                 .value=${getFlowValue}
+                .name=${this.name}
                 ?blankable=${!this.required}
             >
             </ak-search-select>