Export basic low pass filter

Description

• This MR exports a basic signal processing interface, and a low pass filter
• This is needed as a part of the vehicle interface which will be exported later
• I might fight for certain parts of the API (or open a ticket) if the vehicle_interface depends on it
• For more details, see the issue which will be linked below.

Notes for Reviewer

Checklist

• Documentation was updated

Closes #227 (closed)