Separate morango pull/push clients with better write locking and better cancellation handling

[bjester]

Summary

This PR integrates the latest morango changes in this PR, and only uses the db_write_task_lock when data is queuing or dequeuing locally. This also attempts to address cancellation during the stages of a sync task, since we should only allow cancellation when we can expect that the cancellation will occur as expected. For instance, attempting to cancel during a remote dequeuing shouldn't be allowed, as we don't have that control over the remote's processing.

Also addresses the issues with blank passwords as shown in #7127 by setting any blank passwords to NOT_SPECIFIED when deserializing.

No cancel button shown when locally integrating received data, or aka local dequeuing. Also progress is indeterminate.

Reviewer guidance

• Utilize the UI to schedule a sync
• Use the management command to sync a facility
• Ensure cancelling during transfer works as expected
• Cancel button shouldn't appear when the task is in a uncancellable stage

References

Depends on: learningequality/morango#85
Related: #7125
Resolves: #7127

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Contributor Checklist

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• PR has the correct target branch and milestone
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Testing:

• Contributor has fully tested the PR manually
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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

[codecov]

Codecov Report

Merging #7251 into release-v0.14.x will increase coverage by 0.08%.
The diff coverage is 24.00%.

Impacted Files	Coverage Δ
kolibri/core/auth/management/commands/sync.py	0.00% <0.00%> (ø)
kolibri/core/tasks/worker.py	84.07% <ø> (ø)
kolibri/core/auth/models.py	91.26% <80.00%> (-0.09%)	⬇️
kolibri/core/tasks/api.py	44.12% <100.00%> (+0.27%)	⬆️
kolibri/core/tasks/job.py	78.12% <100.00%> (+1.98%)	⬆️
kolibri/core/tasks/storage.py	86.23% <100.00%> (+0.20%)	⬆️
...i/plugins/device/assets/src/views/syncTaskUtils.js	65.38% <100.00%> (+0.67%)	⬆️
...bri/core/content/utils/importability_annotation.py	50.80% <0.00%> (-13.12%)	⬇️
kolibri/core/auth/middleware.py	88.37% <0.00%> (-11.63%)	⬇️
kolibri/core/content/models.py	82.35% <0.00%> (-5.15%)	⬇️
... and 56 more

[rtibbles]

Could simplify some of this slightly by saving the change in cancellable. This will need a bit of enhancement of the job API to add a save method, so I think we can skip this for now, and clean this up in later refactor.

Overall approach looks sound.

[rtibbles]

Looks good to me - have not done any manual testing, but the code changes look right. Let's merge this to do bug bashing on it.