Rename `parameter_values` to `parameter_vectors` in primitives

What should we add?

I have been bothered lately by the fact the we call parameter_values to a Sequence[Sequence[float]] in the primitives, and I think it is leading to confusion.

I keep coming across with loops like:

for parameter_value in parameter_values:
    ...

which seems intuitive but it is semantically wrong, because the type of parameter_value here is Sequence[float].

I wanted to propose renaming ~paramenter_values~ to parameter_bindings. This will make everything more clear imho:

for binding in parameter_bindings:
    for value in binding:
        ...

[ikkoham]

transpile’s argument is circuits. We used it for consistency.

[Cryoris]

The ParameterVector nicely solves some problems we had with parameterized ansätze, like sorting by index if the name is the same (to sort a b[0] b[1] b[2] ... z instead of a b[0] b[1] b[10] .... z) and adjusting the number of parameters if the ansatz is resized (which e.g. TwoLocal circuits allow) 😄 I see how parameter_vectors is confusing as name, maybe we need to choose something else in that case 🤔