Add searchAndFilterStrings translator into kolibri-common

[AlexVelezLl]

Summary

Create searchAndFIlterStrings translator, and migrate existing commonLearnStrings from SearchFiltersPanel.

References

Closes #12609

Reviewer guidance

There was just one string from commonLearnStrings in the SearchFiltersPanel folder. So just check that this string is visible in the UI, and that no more strings from commonLearnStrings are in the SearchFiltersPanel.

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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.211.g7c633a37.pex
Windows Installer (EXE)	kolibri-0.17.0a0.dev0+git.211.g7c633a37-windows-setup-unsigned.exe
Debian Package	kolibri_0.17.0a0.dev0+git.211.g7c633a37-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.17.0a0.dev0+git.211.g7c633a37.dmg
Android Package (APK)	kolibri-0.17.0a0.dev0+git.211.g7c633a37-0.1.4-debug.apk
TAR file	kolibri-0.17.0a0.dev0+git.211.g7c633a37.tar.gz
WHL file	kolibri-0.17.0a0.dev0+git.211.g7c633a37-py2.py3-none-any.whl

[marcellamaki]

thank you @AlexVelezLl!