Fix NPE when invoking copyNecessaryFilesFromCurrentPackage() method on Android

[Rob X (robxyy)]

Fix#2087. It looks like NPE is caused by CodePushUpdateManager.java#L79. When invoking copyNecessaryFilesFromCurrentPackage() method, If currentPackageFolderPath is null, copying currentPackageFolderPath to newUpdateFolderPath will be discarded.

[Dmitriy Kirakosyan (DmitriyKirakosyan)]

Hi Rob X (@robxyy) , thank you for the contribution! Let me leave a couple of comments on your change.

[Djordje (DordeDimitrijev)]

Hi Rob X (@robxyy) these changes were reverted from release 8.3.0 of rn-codepush and latest 8.3.1 hotfix doesn't include them. Reason behind this is that customers reported rollbacks of update and I traced it back to these changes. If you wish to keep these changes and resolve this issue take a look #2725

[Rob X (robxyy)]

Hi Rob X (@robxyy) these changes were reverted from release 8.3.0 of rn-codepush and latest 8.3.1 hotfix doesn't include them. Reason behind this is that customers reported rollbacks of update and I traced it back to these changes. If you wish to keep these changes and resolve this issue take a look #2725

Sorry to hear that. I missed FileUtils.copyDirectoryContents(currentPackageFolderPath, newPackageFolderPath);, and I will push a PR later.