Improve loading UX on some places in Coach

[MisRob]

Summary

• Updates Kolibri to the KDS version Add supporting code for Kolibri loaders kolibri-design-system#448 (temporary fork reference, will be replaced) to include work done in support for this PR
• Fixes and improvements of toggling visibility in the lessons list in Coach > Plan:
  • NaN B in size column doesn't show anymore
    • By re-ordering async events
  • Addresses unresponsive toggle switch on slow networks and prevents from repeated clicks
    • By showing a loader and re-ordering async events to achieve consistency

Last item affects UX on faster networks as well. To prevent from jarring UX, a loader will be displayed for at least 2 seconds even when all requests have finished. Hopefully this helps overall to make UX feel trustworthy taking into account that toggling a lesson visibility is an important operation that would ideally give coaches some feedback.

	Before	After
Slow network
Fast network

References

Fixes #10797

Reviewer guidance

Toggle lessons visibility in Plan > Coach on fast network as well as slow network (you can use network throttling in browser dev tools)

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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

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.16.0b6.dev0_git.7.g1d5ddf6a.pex
Windows Installer (EXE)	kolibri-0.16.0b6.dev0+git.7.g1d5ddf6a-unsigned.exe
Debian Package	kolibri_0.16.0b6.dev0+git.7.g1d5ddf6a-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.16.0b6.dev0+git.7.g1d5ddf6a-0.3.0.dmg
Android Package (APK)	kolibri-0.16.0b6.dev0+git.7.g1d5ddf6a-0.1.0-debug.apk
TAR file	kolibri-0.16.0b6.dev0+git.7.g1d5ddf6a.tar.gz
WHL file	kolibri-0.16.0b6.dev0+git.7.g1d5ddf6a-py2.py3-none-any.whl

[pcenov]

Thanks @MisRob I confirm that the issue described in #10797 is now fixed!

[nucleogenesis]

This looks great. I really love seeing the show being used in a real use case. It looks like a real pleasure to use and I hope I get a chance to integrate it into other places where our loaders are used!

[MisRob]

KDS reference updated