Transition post-processing pipeline infrastructure to the Hamilton library

[leroyvn]

Description

Not ready for merge

This PR transitions our post-processing pipelines to the Hamilton library. This addresses the following issues we had:

• The old pipeline steps are objects with hidden state, which makes understanding what they do, testing them and debugging them very complicated.
• Adding data checks would have required additional implementation work; Hamilton has a validation framework, which we don't use yet, but it will be there when we'll have time to work on this.
• Hamilton has graph representation features which we can now use to visualize the post-processing pipeline.
• It is now very simple to intercept intermediate data and execute only part of the pipeline. This, in particular, makes it possible to get raw data and delay post-processing if the user wants to do so.

Changes are as follows:

• Registered modes are now stored as Mode instances (allows to build filtered mode lists based on mode flags).
• The mi_render() function was fixed to solved an array-to-int conversion bug.
• DistantFluxMeasure can now be instantiated with the factory alias distantflux.
• The BinSet class's interface is extended with properties returning bin bounds and centres.
• The BinSet and WavelengthSet classes now inherit from a common parent type SpectralSet. This is required to use these types in a Hamilton pipeline.
• The spectral subpackage got a testing makeover and underwent some refactoring to make it easier to maintain.
• The MultiDeltaSpectrum underwent refactoring and a testing makeover for improved maintainability.
• The post-processing infrastructure now uses the Hamilton framework.
• A detailed tutorial on post-processing pipelines is now included in the documentation.

To do

• Add API docs
• Verify that tutorials still run as expected
• Add user guide / tutorial
• Document changes

Checklist

• The code follows the relevant coding guidelines
• The code generates no new warnings
• The code is appropriately documented
• The code is tested to prove its function
• The feature branch is rebased on the current state of the main branch
• I updated the change log if relevant
• I give permission that the Eradiate project may redistribute my contributions under the terms of its license