Feature Request: check file hash before skip

[Ovear]

Description

kemono-dl skip download directly when file existed, and --overwrite option will download every file which usually take a plenty of time. Since we can get hash of files, it's would be great to verfity file before skip to keep file from corrupt. I will try to implement this feature recently, hope this helps.

[afterdelight]

Please make a commit, the author of this program is not active anymore