Announce result counts whenever it changes due to search

Problem/Motivation

Steps to reproduce

Proposed resolution

Remaining tasks

• ✅ File an issue about this project
• ☐ Addition/Change/Update/Fix to this project
• ☐ Testing to ensure no regression
• ☐ Automated unit/functional testing coverage
• ☐ Developer Documentation support on feature change/addition
• ☐ User Guide Documentation support on feature change/addition
• ☐ Code review from 1 Drupal core team member
• ☐ Full testing and approval
• ☐ Credit contributors
• ☐ Review with the product owner
• ☐ Release

User interface changes

API changes

Data model changes

Release notes snippet