Reset searchbox input value when search term is cleared

[jredrejo]

Summary

When search terms are cleared in the filters, the search input box must be cleared

References

Closes: #8840

Reviewer guidance

1. Type some search term in the Keywords input box in the Learn-Library tab
2. Click on the "Clear all" link on the right or on the chip containing the written term
3. The Keywords input box should be cleared

Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[rtibbles]

Code looks right, manual testing checks out.