Support in-dashboard notifications for newly-landed translations

[stevejalim]

When a translation lands in Wagtail from Smartling, we send a translation_imported signal, which the containing project can handle to, say, send an email to an appropriate group of users so they know they need to publish certain pages.

Sending an email, however, can be leaky and/or noisy, depending on what's landing back from Smartling.

What would be nicer is a task list on the dashboard.

Initial spec thoughts:

• For each translation of each content object (Page and Snippet) that needs to be published, we create a task
• That task should be shown to all relevant users
• Relevant users are members of a (new) "Translation Approval" Group
• Publishing the content will clear the task for all users in the group

[stevejalim]

I'm hoping we can do this with Wagtail's Task model

[stevejalim]

Talking more with @peiying2 and also seeing some real-world jobs flow through, I can see that we face a real challenge in not only keeping track of what pages need to be published (which we could handle via Tasks, hopefully), but also a way to quickly audit what pages have/have not been translated (both in terms of not sent to Smartling at all, and sent to Smartling but not back yet.)

There is a "Smartling Jobs" view, which is handy for seeing the status of the Job, but not 'What has been, needs to be or is currently being localized yet?'. All the data exists for that, and wagtail-localize has a Translations report, but that doesn't cover this fully, either.

I'll work up a light spec doc to shape some ideas and see what people think.

[stevejalim]

OK, here's a light spec solution for they two key issues. Feedback welcome @robhudson @zerolab @pmac https://docs.google.com/document/d/1DQC3ISQFyxMvQCk03SLI3F1S4VxKBMusjV0J1oRg07M/edit?tab=t.0