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.

source-api/src/commonMain/kotlin/eu/kanade/tachiyomi/source/Source.kt

@@ -27,7 +27,7 @@ interface Source {
     /**
      * Get the updated details for a manga.
      *
-     * @since extensions-lib 1.4
+     * @since extensions-lib 1.5
      * @param manga the manga to update.
      * @return the updated manga.
      */
@@ -39,7 +39,7 @@ interface Source {
     /**
      * Get all the available chapters for a manga.
      *
-     * @since extensions-lib 1.4
+     * @since extensions-lib 1.5
      * @param manga the manga to update.
      * @return the chapters for the manga.
      */
@@ -52,7 +52,7 @@ interface Source {
      * Get the list of pages a chapter has. Pages should be returned
      * in the expected order; the index is ignored.
      *
-     * @since extensions-lib 1.4
+     * @since extensions-lib 1.5
      * @param chapter the chapter.
      * @return the pages for the chapter.
      */
@@ -61,41 +61,24 @@ interface Source {
         return fetchPageList(chapter).awaitSingle()
     }
 
-    /**
-     * Returns an observable with the updated details for a manga.
-     *
-     * @param manga the manga to update.
-     */
     @Deprecated(
         "Use the non-RxJava API instead",
         ReplaceWith("getMangaDetails"),
     )
-    fun fetchMangaDetails(manga: SManga): Observable<SManga> = throw IllegalStateException(
-        "Not used",
-    )
+    fun fetchMangaDetails(manga: SManga): Observable<SManga> =
+        throw IllegalStateException("Not used")
 
-    /**
-     * Returns an observable with all the available chapters for a manga.
-     *
-     * @param manga the manga to update.
-     */
     @Deprecated(
         "Use the non-RxJava API instead",
         ReplaceWith("getChapterList"),
     )
-    fun fetchChapterList(manga: SManga): Observable<List<SChapter>> = throw IllegalStateException(
-        "Not used",
-    )
+    fun fetchChapterList(manga: SManga): Observable<List<SChapter>> =
+        throw IllegalStateException("Not used")
 
-    /**
-     * Returns an observable with the list of pages a chapter has. Pages should be returned
-     * in the expected order; the index is ignored.
-     *
-     * @param chapter the chapter.
-     */
     @Deprecated(
         "Use the non-RxJava API instead",
         ReplaceWith("getPageList"),
     )
-    fun fetchPageList(chapter: SChapter): Observable<List<Page>> = Observable.empty()
+    fun fetchPageList(chapter: SChapter): Observable<List<Page>> =
+        throw IllegalStateException("Not used")
 }