Parse default parameters

Just as for the [json2args](https://github.com/hydrocode-de/json2args) and [json2aRgs](https://github.com/VForWaTer/json2aRgs) packages, the function [getParameters.m](https://github.com/VForWaTer/tool_template_octave/blob/main/src/getParameters.m) must be extended to parse `default` parameters correctly according to the [tool specification](https://github.com/VForWaTer/tool-specs).