Add the Sample DLL implementation into Samples.zip

After downloading the `Samples.zip` file from the [Sample implementations](https://github.com/AdobeDocs/developers-animatesdk-docs/blob/master/Introduction/Sample_implementations.md#sample-implementations) and unzipping it, the archive appears not to contain the `dllSampleComputeSum` folder, although it should have been there, as noted at [Sample DLL](https://github.com/AdobeDocs/developers-animatesdk-docs/blob/master/Introduction/Sample_implementations.md#sample-dll).

The sample DLL should be added to the archive to prevent confusion.

Read Introduction/Sample_implementations.md and inspect the linked Samples.zip archive, focusing on the documented Sample DLL and the missing dllSampleComputeSum folder. Confirm the archive includes the sample DLL implementation and that its contents match the documentation before verifying the downloaded archive after rebuilding or updating it.

Written by the indexing model from the issue text.