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.

(cherry picked from commit 26c5d761da4ba577481f41e63f03952b8a6c323f)

# Conflicts:
#	data/src/main/java/tachiyomi/data/source/SourcePagingSource.kt
#	source-api/src/commonMain/kotlin/eu/kanade/tachiyomi/source/online/HttpSource.kt
#	source-api/src/commonMain/kotlin/eu/kanade/tachiyomi/source/online/HttpSourceFetcher.kt

source-api/src/commonMain/kotlin/exh/source/DelegatedHttpSource.kt

@@ -146,11 +146,17 @@ abstract class DelegatedHttpSource(val delegate: HttpSource) : HttpSource() {
      *
      * @param page the page number to retrieve.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getPopularManga"))
     override fun fetchPopularManga(page: Int): Observable<MangasPage> {
         ensureDelegateCompatible()
         return delegate.fetchPopularManga(page)
     }
 
+    override suspend fun getPopularManga(page: Int): MangasPage {
+        ensureDelegateCompatible()
+        return delegate.getPopularManga(page)
+    }
+
     /**
      * Returns an observable containing a page with a list of manga. Normally it's not needed to
      * override this method.
@@ -159,21 +165,33 @@ abstract class DelegatedHttpSource(val delegate: HttpSource) : HttpSource() {
      * @param query the search query.
      * @param filters the list of filters to apply.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getSearchManga"))
     override fun fetchSearchManga(page: Int, query: String, filters: FilterList): Observable<MangasPage> {
         ensureDelegateCompatible()
         return delegate.fetchSearchManga(page, query, filters)
     }
 
+    override suspend fun getSearchManga(page: Int, query: String, filters: FilterList): MangasPage {
+        ensureDelegateCompatible()
+        return delegate.getSearchManga(page, query, filters)
+    }
+
     /**
      * Returns an observable containing a page with a list of latest manga updates.
      *
      * @param page the page number to retrieve.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getLatestUpdates"))
     override fun fetchLatestUpdates(page: Int): Observable<MangasPage> {
         ensureDelegateCompatible()
         return delegate.fetchLatestUpdates(page)
     }
 
+    override suspend fun getLatestUpdates(page: Int): MangasPage {
+        ensureDelegateCompatible()
+        return delegate.getLatestUpdates(page)
+    }
+
     /**
      * Returns an observable with the updated details for a manga. Normally it's not needed to
      * override this method.
@@ -250,19 +268,15 @@ abstract class DelegatedHttpSource(val delegate: HttpSource) : HttpSource() {
      *
      * @param page the page whose source image has to be fetched.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getImageUrl"))
     override fun fetchImageUrl(page: Page): Observable<String> {
         ensureDelegateCompatible()
         return delegate.fetchImageUrl(page)
     }
 
-    /**
-     * Returns an observable with the response of the source image.
-     *
-     * @param page the page whose source image has to be downloaded.
-     */
-    override fun fetchImage(page: Page): Observable<Response> {
+    override suspend fun getImageUrl(page: Page): String {
         ensureDelegateCompatible()
-        return delegate.fetchImage(page)
+        return delegate.getImageUrl(page)
     }
 
     /**

source-api/src/commonMain/kotlin/exh/source/EnhancedHttpSource.kt

@@ -149,8 +149,11 @@ class EnhancedHttpSource(
      *
      * @param page the page number to retrieve.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getPopularManga"))
     override fun fetchPopularManga(page: Int) = source().fetchPopularManga(page)
 
+    override suspend fun getPopularManga(page: Int) = source().getPopularManga(page)
+
     /**
      * Returns an observable containing a page with a list of manga. Normally it's not needed to
      * override this method.
@@ -159,16 +162,23 @@ class EnhancedHttpSource(
      * @param query the search query.
      * @param filters the list of filters to apply.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getSearchManga"))
     override fun fetchSearchManga(page: Int, query: String, filters: FilterList) =
         source().fetchSearchManga(page, query, filters)
 
+    override suspend fun getSearchManga(page: Int, query: String, filters: FilterList) =
+        source().getSearchManga(page, query, filters)
+
     /**
      * Returns an observable containing a page with a list of latest manga updates.
      *
      * @param page the page number to retrieve.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getLatestUpdates"))
     override fun fetchLatestUpdates(page: Int) = source().fetchLatestUpdates(page)
 
+    override suspend fun getLatestUpdates(page: Int) = source().getLatestUpdates(page)
+
     /**
      * Returns an observable with the updated details for a manga. Normally it's not needed to
      * override this method.
@@ -224,14 +234,10 @@ class EnhancedHttpSource(
      *
      * @param page the page whose source image has to be fetched.
      */
+    @Deprecated("Use the non-RxJava API instead", replaceWith = ReplaceWith("getImageUrl"))
     override fun fetchImageUrl(page: Page) = source().fetchImageUrl(page)
 
-    /**
-     * Returns an observable with the response of the source image.
-     *
-     * @param page the page whose source image has to be downloaded.
-     */
-    override fun fetchImage(page: Page) = source().fetchImage(page)
+    override suspend fun getImageUrl(page: Page) = source().getImageUrl(page)
 
     /**
      * Returns the response of the source image.