Refactor usesearch

[AlexVelezLl]

Summary

Finish refactor of useSearch in Learn to extend useBaseSearch.

References

Closes #12517.

Reviewer guidance

Run the server and see that search

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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

• 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

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.17.0a0.dev0_git.105.g49536b34.pex
Windows Installer (EXE)	kolibri-0.17.0a0.dev0+git.105.g49536b34-windows-setup-unsigned.exe
Debian Package	kolibri_0.17.0a0.dev0+git.105.g49536b34-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.17.0a0.dev0+git.105.g49536b34.dmg
Android Package (APK)	kolibri-0.17.0a0.dev0+git.105.g49536b34-0.1.4-debug.apk
TAR file	kolibri-0.17.0a0.dev0+git.105.g49536b34.tar.gz
WHL file	kolibri-0.17.0a0.dev0+git.105.g49536b34-py2.py3-none-any.whl

[rtibbles]

Nothing blocking - just a couple of questions, and we could perhaps make the diff more minimal in some places.

Not quite sure why tests are failing, but we definitely need to fix that before merge!

[rtibbles]

Minimal diff, maximum impact! Manual testing checks out for both local and remote library searching, in the main Library page and in topics.