[Issue] Adding failure callback to ui file uploader

[m2-assistant]

This issue is automatically created based on existing pull request: #27092: Adding failure callback to ui file uploader

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Summary (*)

Magento 2.4-develop
Magento_Ui file uploader works fine. However, recently when I have used it for custom file upload, and when I had error while uploading file there was no info what happened. Uploader just stopped uploading. After debugging it turned out it was 413 from nginx, and next steps were clear (bumping post, upload and client body size). I think if we have an error we should get info in dev tools console.

Magento_Downloadable file uploader in adminhtml is heavily based on this uploader, so whole thing can be investigated and tested while creating downloadable product.
By the way, I had refactored formatting a little bit.

Examples (*)

1. Open downloadable product form
2. Try to upload huge file exceeding nginx and php limitations (especially client_max_body_size)
3. There is no info, uploader just stops working.

Proposed solution

[m2-assistant]

Hi @engcom-Delta. Thank you for working on this issue.
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