use correct gradle packageTask and asserts dir for android libraries (#32026)

Summary:
Fixes #29577 and react-native-community/upgrade-support#93, when building an android library the package task has a different name, which was not handled correctly in the react.gradle file. The fix uses the existing `packageTask` variable which is correctly set for applications and libraries. This PR also copies the bundled js file into the correct assets directory, which is different from the assets directory of applications.

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[Android] [Fixed] - Fixed Android library builds with react.gradle file

Pull Request resolved: #32026

Test Plan: Tested with my android library build which includes the `react.gradle` file and the build succeeded.

Reviewed By: sshic, ShikaSD

Differential Revision: D30368771

Pulled By: cortinico

fbshipit-source-id: 8f0df8c4d0fa38d85f7c0b9af56d88799571191d

Author: Legion2

react.gradle

@@ -284,25 +284,32 @@ afterEvaluate {
                 into(file(config."jsBundleDir${targetName}"))
             } else {
                 into ("$buildDir/intermediates")
-                into ("assets/${targetPath}") {
-                    from(jsBundleDir)
-                }
+                if (isAndroidLibrary) {
+                    into ("library_assets/${variant.name}/out") {
+                        from(jsBundleDir)
+                    }
+                } else {
+                    into ("assets/${targetPath}") {
+                        from(jsBundleDir)
+                    }
 
-                // Workaround for Android Gradle Plugin 3.2+ new asset directory
-                into ("merged_assets/${variant.name}/merge${targetName}Assets/out") {
-                    from(jsBundleDir)
-                }
+                    // Workaround for Android Gradle Plugin 3.2+ new asset directory
+                    into ("merged_assets/${variant.name}/merge${targetName}Assets/out") {
+                        from(jsBundleDir)
+                    }
 
-                // Workaround for Android Gradle Plugin 3.4+ new asset directory
-                into ("merged_assets/${variant.name}/out") {
-                    from(jsBundleDir)
+                    // Workaround for Android Gradle Plugin 3.4+ new asset directory
+                    into ("merged_assets/${variant.name}/out") {
+                        from(jsBundleDir)
+                    }
                 }
             }
 
             // mergeAssets must run first, as it clears the intermediates directory
             dependsOn(variant.mergeAssetsProvider.get())
 
             enabled(currentBundleTask.enabled)
+            dependsOn(currentBundleTask)
         }
 
         // mergeResources task runs before the bundle file is copied to the intermediate asset directory from Android plugin 4.1+.
@@ -352,8 +359,7 @@ afterEvaluate {
         }
 
         if (enableVmCleanup) {
-            def task = tasks.findByName("package${targetName}")
-            task.doFirst(vmSelectionAction)
+            packageTask.doFirst(vmSelectionAction)
         }
     }
 }