Paste directly to upload pictures/files

Summary | 概述:
Add feature of paste directly to upload pictures/files

Type | 类型: add

BUG: https://iron.lily-is.land/T3

Test Plan | 测试计划:
Copy a picture or some file urls into clipboard, then paste them into SendMessageBox's textArea, seeing the popup opened and the file can be uploaded successfully

Co-authored-by: tusooa <tusooa@kazv.moe>
Reviewed-by: tusooa <tusooa@kazv.moe>
Approved-by: tusooa <tusooa@kazv.moe>

GitLab Merge Request: https://lily-is.land/kazv/kazv/-/merge_requests/109