Fix snackbar errors in content import

[rtibbles]

Summary

• Regression caused by Vue 2.7 upgrade
• Use the composable in module scope, as can't define setup on a mixin if the consuming component also defines setup.

References

Follow up from #12933

Reviewer guidance

Import content into Kolibri, confirm that snackbars are displayed, without errors, and that redirects happen properly

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.18.0a0.dev0_git.150.g751d70c6.pex
Windows Installer (EXE)	kolibri-0.18.0a0.dev0+git.150.g751d70c6-windows-setup-unsigned.exe
Debian Package	kolibri_0.18.0a0.dev0+git.150.g751d70c6-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.18.0a0.dev0+git.150.g751d70c6.dmg
Android Package (APK)	kolibri-0.18.0a0.dev0+git.150.g751d70c6-0.1.4-debug.apk
Raspberry Pi Image	kolibri-pi-image-0.18.0a0.dev0+git.150.g751d70c6.zip
TAR file	kolibri-0.18.0a0.dev0+git.150.g751d70c6.tar.gz
WHL file	kolibri-0.18.0a0.dev0+git.150.g751d70c6-py2.py3-none-any.whl

[nucleogenesis]

I didn't get the "Task finished" snackbar but I don't suspect that is related to your changes here.

I have a video but GH isn't uploading it correctly ping me on Slack if you want it

[pcenov]

Yeah, I also confirm that "Task started" is shown correctly every time, but no trace of "Task finished". Checked in Kolibri 0.17.4 and it's not shown there as well, so this might have been broken a long time ago.

[rtibbles]

@pcenov could you file an issue for the lack of Task Finished? Interesting that it's happening in 0.17 as well, because that's before we did a bunch of changes here!

[nucleogenesis]

Code looks good and w/ the follow-up issue filed this is good to go