Add Deep Learning functionality
This patch adds support for Deep Learning functionality to elsa. The new elsa ml module consists of three libraries:
- elsa_ml: Contains the high-level API as well as generic internals.
- elsa_ml_dnnl_backend: Contains all functionality specific to the oneDNN (former DNNL) backend.
- elsa_ml_cudnn_backend: Contains all functionality specific to the Nvidia CuDNN backend.