Add more replacement suspend functions for source APIs

These are basically 1-to-1 replacements for the existing RxJava APIs.
This will make the initial migration off of RxJava simpler. We'll
revisit the actual call flows in followup versions of the API.

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/globalsearch/SearchScreenModel.kt

@@ -19,7 +19,6 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
-import tachiyomi.core.util.lang.awaitSingle
 import tachiyomi.domain.manga.interactor.GetManga
 import tachiyomi.domain.manga.interactor.NetworkToLocalManga
 import tachiyomi.domain.manga.model.Manga
@@ -140,7 +139,7 @@ abstract class SearchScreenModel(
 
                     try {
                         val page = withContext(coroutineDispatcher) {
-                            source.fetchSearchManga(1, query, source.getFilterList()).awaitSingle()
+                            source.getSearchManga(1, query, source.getFilterList())
                         }
 
                         val titles = page.mangas.map {