Enable adding parameters back into a circuit with specific values

[eileen-kuehn]

In case parameters, that is gates, are added back into a circuit the current cost will change depending on the parameter value. E.g. in case a rotation is not set to 0 the loss will probably drop immediately. To enable a smoother training it might therefore be useful to configure a specific value, such as 0, when adding parameters. In case of rotations this would result in an identity transformation not influencing the current loss.
Adding parameters always with 0 however might reduce the chance to directly reduce the loss.