Attachments upload core arches3

[TeriForey]

Description of Change

Revisited the attachments bulk upload feature and added better error messages, and an undo button to remove the resources that had just been uploaded.

Issues Solved

113

Types of changes

• [X] Bugfix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• [ ] Unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)

Further comments