Add methods to get manga and chapter url (#8114)

* Add methods to get manga and chapter url

Some fork supports directly opening chapters with webview hence `getChapterUrl`

* Review Changes

* Add since to javadoc

source-api/src/main/java/eu/kanade/tachiyomi/source/online/HttpSource.kt

@@ -356,6 +356,28 @@ abstract class HttpSource : CatalogueSource {
         }
     }
 
+    /**
+     * Returns the url of the provided manga
+     *
+     * @since extensions-lib 1.4
+     * @param manga the manga
+     * @return url of the manga
+     */
+    open fun getMangaUrl(manga: SManga): String {
+        return mangaDetailsRequest(manga).url.toString()
+    }
+
+    /**
+     * Returns the url of the provided chapter
+     *
+     * @since extensions-lib 1.4
+     * @param chapter the chapter
+     * @return url of the chapter
+     */
+    open fun getChapterUrl(chapter: SChapter): String {
+        return pageListRequest(chapter).url.toString()
+    }
+
     /**
      * Called before inserting a new chapter into database. Use it if you need to override chapter
      * fields, like the title or the chapter number. Do not change anything to [manga].