Unreal使用GooglePAD生成AAB包，并加在fast-follow资源

1.修改obbfilter，设置需要添加到obb的pak文件

2.修改项目设置，打AAB包

3.cook stage生成所有Paks文件

4.将部分pak文件拷贝到Intermediate/Android/arm64/gradle/assetpacks/fast-follow/包名/src/main/assets文件夹下，GooglePad插件的XML会自动将ast-follow/XXXX文件夹识别为fast-follow包，install-time不需要设置，默认会把obb打进去

5.打包完成后，安装AAB文件，使用GooglePad api读取Fast-follow资源

点击查看代码

int32 GetStatus(EGooglePADDownloadStatus& InDownResult)
{
	int32 TmpDownloadStatus = -1;
	EGooglePADErrorCode res3 = UGooglePADFunctionLibrary::GetDownloadState("SecPaks", TmpDownloadStatus);
	InDownResult = UGooglePADFunctionLibrary::GetDownloadStatus(TmpDownloadStatus);
	UE_LOG(GoogleAAB, Log, TEXT("chenghh download status: %d"), static_cast<int32>(InDownResult));
	return TmpDownloadStatus;

}

void UHotUpdateManager::StartAssetDownload()
{
	IPlatformFile& PlatformFile = FPlatformFileManager::Get().GetPlatformFile();

	EGooglePADErrorCode res1 = UGooglePADFunctionLibrary::RequestInfo({"SecPaks"});
	UE_LOG(GoogleAAB, Log, TEXT("RequestInfo result: %d"), static_cast<int32>(res1));
	EGooglePADErrorCode res2 = UGooglePADFunctionLibrary::RequestDownload({"SecPaks"});
	UE_LOG(GoogleAAB, Log, TEXT("RequestDownload result: %d"), static_cast<int32>(res2));

	EGooglePADDownloadStatus GetStatusRes = EGooglePADDownloadStatus::AssetPack_UNKNOWN;
	int32 StateId = GetStatus(GetStatusRes);
	while (GetStatusRes != EGooglePADDownloadStatus::AssetPack_DOWNLOAD_COMPLETED)
	{
		UGooglePADFunctionLibrary::ReleaseDownloadState(StateId);
		StateId = GetStatus(GetStatusRes);
	}

	int32 Location = -1;
	EGooglePADErrorCode Code = UGooglePADFunctionLibrary::GetAssetPackLocation("SecPaks", Location);
	UE_LOG(GoogleAAB, Log, TEXT("Asset pack location: %d"), Location);
	FString AssetPath = UGooglePADFunctionLibrary::GetAssetsPath(Location);
	if (!AssetPath.IsEmpty())
	{
		PlatformFile.DirectoryExists(*AssetPath);
		UE_LOG(GoogleAAB, Log, TEXT("Asset pack Path: %s"), *AssetPath);
		FString PakAssetPath = AssetPath + "/Paks";
		if (PlatformFile.DirectoryExists(*PakAssetPath))
		{
			PlatformFile.FindFiles(AssetNames, *PakAssetPath, TEXT(".pak"));
            ........
		}
	}

	UGooglePADFunctionLibrary::ReleaseAssetPackLocation(Location);
	UGooglePADFunctionLibrary::ReleaseDownloadState(StateId);
}