VQE and Optimizer refactoring

[Cryoris]

Summary

Refactor the VQE and the Optimizers according to the design doc.

Details

This refactor entails at least

• Making VQE stateless (Make VQE stateless #6380)
• Refactoring the Optimizer interface to use minimize (Refactor the Optimizer interface #6382)
• Allowing callables as optimizers in VQE (Allow callables as optimizers in VQE #6383)

And optionally

• Use parameter order of circuits instead of re-sorting by name in VQE (Remove explicit parameter sorting from algorithms #5953, Not expected ordering of parameters in energy evaluation call #5721)
• Removing/Reducing VariationalAlgorithm to an interface (Remove or reduce VariationalAlgorithm #6384)
• Make Optimizers serializable (for usage with Qiskit Runtime) (Enable serialization of Optimizers #6385)
• Streamline VQE's interface by removing little used methods/arguments

[Cryoris]

I'm closing this since all items from the design doc concerning the VQE have been addressed. Also steppable optimizers are tackled in #8150.