Parameter has no __pow__

[grossardt]

What should we add?

from qiskit.circuit import Parameter
a = Parameter('a')
a**2

will raise a TypeError: unsupported operand type(s) for ** or pow(): 'Parameter' and 'int' (tested with qiskit 0.44.1, qiskit-terra 0.25.1).
On the other hand, a**2 can be easily constructed as (2 * a.log()).exp() which yields ParameterExpression(a**2)

It seems reasonable to also implement Paramater.__pow__ at least for int or float powers? Or is there a reason why this is not implemented that I am missing?

[kevinsung]

Duplicate of #8959

[grossardt]

Duplicate of #8959

Dang, missed that when searching. Thanks!