Name-ordered circuit parameters

[Cryoris]

Summary

Return the circuit parameters sorted by name and allow binding parameters by list of values. Closes #5557 and #5614.

Details and comments

Details are discussed in https://gist.github.com/Cryoris/1bc894e684f381e07a131196bf86a4da.

In a nutshell:

• Circuit parameters are sorted by name. Within parameter-vectors, the value indexing has precedence over the name of the index (i.e. we sort x[0] x[1] x[2] ... x[10] and not x[0] x[1] x[10] x[2] ...)
• The ParameterView object acts as intermediary object between the current return type, which is a set, and a list-like new return type. It implements all set methods but raises a deprecation warning if any is used.
• The {assign, bind}_parameters methods accept iterables to bind all parameters at once, additionally to the {param: value} dictionaries.

In future we can remove the ordered_parameters property of the n-local circuits and let the variational algorithms use the inherent order of circuits instead of explicitly sorting them by name.

[kdk]

Haven't had a chance to review the set methods in depth, but looks good so far.

[ewinston]

Are parameter tables usually small enough that rebuilding won't be too expensive?

[Cryoris]

The tables themselves should be reasonably small, maybe a few hundred elements at max right now. But you've got a point, it would be better to avoid iterating over all gates again (including the unparameterized ones) so I changed the logic to make it more efficient and only work on the parameter tables.

[Cryoris]

Actually it seems we have to rebuild it since instructions are copied and we cannot use the parameter table from the input other. Maybe @kdk has another idea to make it without rebuild 😄

[kdk]

We do something similar in QuantumCircuit.copy:

https://github.com/Qiskit/qiskit-terra/blob/cb2110957e4b22df8d1bfe42e353fae83af2a14b/qiskit/circuit/quantumcircuit.py#L1686

We make the instruction copies ahead of time so that we can build a map from the old to new instances. Then we can use that map to rebuild the parameter table without having to scan and isinstance all the parameters in the circuit. Maybe a similar approach could be useful here.