Avoid syncing with non-kolibris

[bjester]

Summary

• Adds property to NetworkLocation for checking if it's a kolibri
• Updates learner discovery hooks to ensure location is a kolibri
• Updates SoUD context logic to ensure location is a kolibri
• Adds tests

References

Resolves #11468

Reviewer guidance

Start Kolibri

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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

• 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]

All changes make sense - don't expect QA to show any issues, but I'll hold off on approval until regression testing!

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.16.0b6.dev0_git.317.g14a292af.pex
Windows Installer (EXE)	kolibri-0.16.0b6.dev0+git.317.g14a292af-unsigned.exe
Debian Package	kolibri_0.16.0b6.dev0+git.317.g14a292af-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.16.0b6.dev0+git.317.g14a292af-0.3.0.dmg
Android Package (APK)	kolibri-0.16.0b6.dev0+git.317.g14a292af-0.1.0-debug.apk
TAR file	kolibri-0.16.0b6.dev0+git.317.g14a292af.tar.gz
WHL file	kolibri-0.16.0b6.dev0+git.317.g14a292af-py2.py3-none-any.whl

[pcenov]

Works as described. No regressions observed while manually testing.