Indicate w/a dialog when songs are already in playlists

[Leon-Plickat]

Description

I'd like a button to automatically remove duplicate entries from playlists.

Problem solved

I have multiple playlists containing many albums each. Sometimes I accidentally add one or multiple albums twice. Since the lists are really large, checking manually is just not feasible. An option to automatically remove duplicate entries would solve this issue.

Other implementations

Music players for the desktop generally have a different UI/UX for cerating playlists and as such generally don't suffer from the duplication issue in the first place.

I am not familiar with other mobile music players at this moment.

Benefit

Removes annoyance when editing playlists.

Duplicates

• I have checked this feature request for duplicates.
• I have checked that this feature is not implemented in the lastest version.
• I have checked the Why Are These Features Missing? page.
• I agree to the Contribution Guidelines.

[OxygenCobalt]

Duplicate of #451. I've been meaning to improve the duplication experience though, I just have not had time, so I'll rename this issue.