Add interoperability between Awkward Array and ML libraries

[maxymnaumchyk]

This issue is a checklist of different functions that convert Awkward Arrays to ML libraries and backwards.

TensorFlow library

Functions for rectangular arrays

• [ ] ak.from_tensorflow
• [ ] ak.to_tensorflow

Functions for irregular arrays

• [x] ak.from_raggedtensor
• [x] ak.to_raggedtensor #3210
• [ ] add cuda support for ak.to_raggedtensor and ak.from_raggedtensor #3263

PyTorch library

Functions for rectangular arrays

• [x] ak.from_torch
• [x] ak.to_torch #3259

For irregular arrays, a number of functions will be created, for the most flexible and convenient use. Here are the issues opened for this task:

• #3256
• #3257
• #3265 And a useful comment by Jim: https://github.com/scikit-hep/awkward/pull/3246#pullrequestreview-2328831856