[ADD] filter_signal package with non-working Low-Pass Filter

filter_signal/CMakeLists.txt

filter_signal/README.md

filter_signal/config/.gitignore

filter_signal/config/cpp_publisher.yaml

filter_signal/filter_signal/__init__.py

filter_signal/filter_signal/filter.py

filter_signal/filter_signal/filters.py

filter_signal/filter_signal/parameters.py

filter_signal/include/cpp_python_package/cpp_publisher.hpp

filter_signal/launch/cpp_python.launch.py

filter_signal/package.xml

filter_signal/src/cpp_publisher.cpp

filter_signal/src/cpp_publisher_main.cpp