Cleanup Library presenter (#8284)

* yeet observable + minor cleanup

* move [getTracksFlow] to domain

* Lint

* Review changes

Co-Authored-By: Andreas <6576096+ghostbear@users.noreply.github.com>

* Review Changes 2

* Stuff

* Rename + Rebase

* Lint

Co-authored-by: Andreas <6576096+ghostbear@users.noreply.github.com>

app/src/main/java/eu/kanade/domain/track/interactor/GetTracks.kt

@@ -19,10 +19,6 @@ class GetTracks(
         }
     }
 
-    fun subscribe(): Flow<List<Track>> {
-        return trackRepository.getTracksAsFlow()
-    }
-
     fun subscribe(mangaId: Long): Flow<List<Track>> {
         return trackRepository.getTracksByMangaIdAsFlow(mangaId)
     }

app/src/main/java/eu/kanade/domain/track/interactor/GetTracksPerManga.kt

@@ -0,0 +1,20 @@
+package eu.kanade.domain.track.interactor
+
+import eu.kanade.domain.track.repository.TrackRepository
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+
+class GetTracksPerManga(
+    private val trackRepository: TrackRepository,
+) {
+
+    fun subscribe(): Flow<Map<Long, List<Long>>> {
+        return trackRepository.getTracksAsFlow().map { tracks ->
+            tracks
+                .groupBy { it.mangaId }
+                .mapValues { entry ->
+                    entry.value.map { it.syncId }
+                }
+        }
+    }
+}