Add orbital bias correction in processing workflow.

Bias correction between orbits and different satellite platforms is important for ensuring a smooth, accurate and consistent multiplatform water level timeseries. The current implementation is designed so that this processing step can be easily added to the workflow.

Start by locating the processing workflow and the existing extension point mentioned in the issue. Clarify the correction method, required inputs for different orbits and satellite platforms, and validation criteria before implementing the bias-corrected multiplatform water-level timeseries step.

Written by the indexing model from the issue text.