Filter step: Option to choose different buffer methods

[CarlMartinAxel]

Introduces bufferFrames and bufferType as filter step options.
Let's the user choose the number of frames to buffer at each end of the signal and which method to use. This helps reduce edge effects in different ways when filtering. Buffer options include extrapolation, reflection and constant padding.

Checklist

• Test case implemented
• Test coverage 100%
• Tested inside a yaml pipeline
• Documentation added

Example

Example of using the new filter options.

- parameter: filtered_signal
  steps:
    - lowpass:
      cutoff: 6
      bufferFrames: 20
      bufferType: extrapolation

Work item: AB#39445