Set preview/experimental compiler flags instead of using annotations

(cherry picked from commit 781971ee81)

# Conflicts:
#	app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

app/src/main/java/exh/debug/DebugFunctions.kt

@@ -20,7 +20,6 @@ import exh.metadata.metadata.base.insertFlatMetadata
 import exh.savedsearches.JsonSavedSearch
 import exh.util.cancellable
 import exh.util.jobScheduler
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.asFlow
 import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.toList
@@ -31,7 +30,6 @@ import kotlinx.serialization.json.Json
 import uy.kohesive.injekt.injectLazy
 import java.lang.RuntimeException
 
-@OptIn(FlowPreview::class)
 object DebugFunctions {
     val app: Application by injectLazy()
     val db: DatabaseHelper by injectLazy()