Add ability to add works to existing list from Bulk Search
closes #11348
Feature Requested
Currently the bulk search endpoint is a handy UI to easily support adding many books to a new list. Extending this to add books to an already existing list would be a useful expansion.
### Solution Backend: Reuse the logic behind /lists/add, just extending it to handle adding works to an existing list by ID.
Frontend: When the user clicks “Add to List” on the bulk search page, a dropdown will open showing their existing lists. They can either pick one to add the selected works to or click “Create new list” to go through the current /lists/add flow.
https://github.com/user-attachments/assets/9f149f10-6863-4284-aa6c-a5bb4117f06a
Stakeholders @cdrini
PTAL @cdrini
Updated the /search/bulk page.