Introduce a parameter `input_gradients` to NeuralNetwork

[adekusar-drl]

Introduce a parameter `input_gradients` to NeuralNetwork

[jonvet]

mind if I take a look at this one?

to confirm:

• NeuralNetwork and all classes that inherit from it should have a new parameter input_gradients
• should the current getter/setter in NeuralNetwork be deprecated?

[adekusar-drl]

I don't mind, any help is appreciated.

Things to do:

• Add input_gradient as a constructor parameter to NeuralNetwork with a default value of False. So, yes, this is the answer on the first question.
• Verify there are getter/setter in place (as I recall there's just a getter). So, no, current getter/setter are not deprecated.
• Remove a line in TorchConnector where input_gradients is set to True since this should be done explicitly by a user. Probably this should be mentioned in the documentation(docstrings).
• Add a line to set input_gradients to True in the torch connector tests.
• May be more unit tests are required, can't say now.
• Add a reno file with the changes.

Also take a look at https://github.com/Qiskit/qiskit-machine-learning/blob/main/CONTRIBUTING.md
Probably that's it. Let me know if you have questions.

[jonvet]

cool thanks, i also have permission from my employer now, so I'll get started