Fix order in which notification updates are commited to state

[MisRob]

Summary

Commit updates to state sorted by timestamp.

References

Fixes #11302 where "Completed" update was commited before "Started" update.

Reviewer guidance

Start a quiz on a full device. Take the quiz on LoD device. Wait for sync to happen and confirm that #11302 is fixed.

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.64.g24505ad9.pex
Windows Installer (EXE)	kolibri-0.16.0b6.dev0+git.64.g24505ad9-unsigned.exe
Debian Package	kolibri_0.16.0b6.dev0+git.64.g24505ad9-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.16.0b6.dev0+git.64.g24505ad9-0.3.0.dmg
Android Package (APK)	kolibri-0.16.0b6.dev0+git.64.g24505ad9-0.1.0-debug.apk
TAR file	kolibri-0.16.0b6.dev0+git.64.g24505ad9.tar.gz
WHL file	kolibri-0.16.0b6.dev0+git.64.g24505ad9-py2.py3-none-any.whl

[rtibbles]

Assuming that the problem is only for the order in which recently received notifications arrive, then this looks like the right fix - if manual QA confirms the fix, this is good to go.

[MisRob]

Assuming that the problem is only for the order in which recently received notifications arrive

I haven't observed any other problems but didn't really dig deep into other places

[pcenov]

Implemented as specified, no regression issues observed.