* Add onnx support for VisionEncoderDecoder * Add onnx support for VisionEncoderDecoder * Removed unused import * Rename encoder hidden state Co-authored-by: lewtun <lewis.c.tunstall@gmail.com> * Update docstrings and removed redundant code * Added test function for enc-dec models * Update doc string text Co-authored-by: lewtun <lewis.c.tunstall@gmail.com> * fixed code style Co-authored-by: lewtun <lewis.c.tunstall@gmail.com>