Implement the prewrapping in the butterworth filter

[GiulioRomualdi]

This pull request introduces the prewrapping technique, enhancing the frequency response consistency of filters across continuous and discrete domains. By implementing this technique, we ensure uniform performance across different signal representations.

The above plot demonstrates the application of the prewrapping technique, resulting in an improvement in the step response of the filter.

Additionally, this PR addresses an issue related to the setInput() method, particularly its compatibility with fixed-size Eigen::Vectors.

Important

By implementing the prewrapping technique, the Butterworth filter now produces results identical to those obtained using MATLAB with the following command:

[z_d,p_d,k_d] = butter(order, cutoff_frequency / (sampling_frequency / 2));

This equivalence holds when the same order, cutoff_frequency, and sampling_frequency parameters are used.