more explicit error messages for file uploads

[rigelk]

Description

File uploads are often met with network errors. They can also be met with classic HTTP errors as defined in our spec. Both are dealt with (reset + notification), but notification messages only last 5 seconds, and their messages are not always describing the code correctly nor left in the console for later investigation. Since users uploading large files or with unleliable connections are not always monitoring their upload page, they might miss a temporary notification.

This PR brings:

• sticky notification option
• notifications log to the console
• some upload errors now trigger sticky notifications
• RP sets a header showing maximum file size for errors

@Chocobozzz are you interested by the maximum file size information being given by the reverse-proxy, or is it superfluous?

Related issues

This issue is related to #324 (comment), and
fixes #3050

Has this been tested?

• 👍 yes, I added tests to the test suite
• 👍 yes, light tests as follows are enough
• 💭 no, because this PR is a draft and still needs work

[rigelk]

@Chocobozzz do you know how I could test that in the CI?

[Chocobozzz]

@Chocobozzz are you interested by the maximum file size information being given by the reverse-proxy, or is it superfluous?

This is a good idea

do you know how I could test that in the CI?

E2E CI?

[Chocobozzz]

What's the status of this PR? I would like to ship it in v3 since upload errors are very frustrating at the moment. But I'm not sure you should use the sticky attribute. Instead, I think we should display the error on top of the upload form, with a retry button.

[rigelk]

@Chocobozzz I’ll keep the notifier refactoring, as sticky messages might come in handy elsewhere.

[rigelk]

I changed the error display so that it both notifies and keep the message in the progressbar, which now has a retry and cancel button. Maybe some errors could disable the retry button (like error 413 which a retry will not help solve).

[Chocobozzz]

Nice!