Close#24195
Some of the changes are taken from my another fix
f07b0de997
in #20147 (although that PR was discarded ....)
The bug is:
1. The old code doesn't handle `removedfile` event correctly
2. The old code doesn't provide attachments for type=CommentTypeReview
This PR doesn't intend to refactor the "upload" code to a perfect state
(to avoid making the review difficult), so some legacy styles are kept.
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Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>