[Feature] Spleeter Models for Tensorflow 2 and tflite (mobile)

## hello, please can we get Spleeter Models for Tensorflow tflite. Or if the functionality is not yet available, how can we convert the current model to be tflite compartible

Start by reviewing the current Spleeter model and the requested TensorFlow Lite target. Determine whether the existing model can be converted and what mobile compatibility requires; the work is done when compatible TensorFlow Lite models are available or the conversion path is documented.

Written by the indexing model from the issue text.