Merge credential files

[YuKitAs]

Different credential files should be able to be merged.

• Add new items
• If name and username are both equal, update password and description with the latest updated timestamp

[xiGUAwanOU]

Hey YuKitAs,

thanks for the issue. This feature is actually already implemented if you import another credential file. The imported credential file will be merged with the current one. But the merge implementation is based on an internal UUID instead of name and username. I personally think that comparing with name and username is not quite reliable. What do you think here?

Best regards,
Watermelon

[YuKitAs]

Relying on unique id sounds better. But sometimes I could create two different entries manually so they will have different IDs. If there is no unique constraint on the name, it just requires some manually cleanup and it would also be fine.