Change QuantumKernel.user_parameters field name in qiskit-machine-learning

[caleb-johnson]

• [ ] Change qiskit_machine_learning.kernels.QuantumKernel.user_parameters field to something else, maybe kernel_parameters or training_parameters. Open to suggestions

• [ ] Ensure QuantumKernel , QuantumKernelTrainer , and qiskit_machine_learning.utils.loss_functions.SVCLoss source are updated to reflect change.

• [ ] Ensure associated unit tests are updated

• [ ] Ensure kernel training tutorial in qiskit-machine-learning is updated

• [ ] Ensure quantum-kernel-training prototype repository notebooks are updated

• [ ] Ensure quantum-kernel-training prototype repository docs and helper source code reflect changes

• [ ] Ensure QKT gist is updated in Github (Caleb)

• [ ] Ensure our two Qiskit blog posts reflect latest usage (Caleb)

The below could be a separate Issue/PR if you prefer

• [ ] Add an error message to QuantumKernelTrainer.fit method that throws when the method has been called but the "[insert_new_name]_parameters" has not been set

[caleb-johnson]

The parameter names have been updated in Qiskit. This issue will remain open until after the next qiskit ML release. We will wait to update blog posts, notebook tutorials and gists until after release.