Add playlist to new collection button present on playlist room

[Layendan]

#31541

Add a button to playlist room that creates a new collection with all the beatmaps present in the playlist.

Current function:

• if collection does not exist: create new playlist with the name of the room
• if a collection with the same name as the room does exist: append unique entries to collection
• will add beatmaps that are not downloaded to the collection. If the user downloads them later on, they will automatically be added to the collection (this means that it is not possible to remove an undownloaded beatmap from the collection until they download it)

Basic run through features

2025-02-06_17-31-07.mp4

Adding beatmaps to existing collection

2025-02-06_17-33-17.mp4

[Layendan]

Videos are outdated: notifications are changed from "Created new playlist" to "Created new collection"