Remove the Dataset logic from PGM core, use DatasetHandler for MainModel

[TonyXiang8787]

Background

Currently we use Dataset as the input view for MainModel, such as:

power-grid-model/power_grid_model_c/power_grid_model/include/power_grid_model/main_model.hpp

Lines 101 to 102 in 9521280

	explicit MainModelImpl(double system_frequency, ConstDataset const& input_data, Idx pos = 0)
	: system_frequency_{system_frequency} {

The C-API receives DatasetHandler, we have a function to export to a Dataset. See blow:

power-grid-model/power_grid_model_c/power_grid_model/include/power_grid_model/auxiliary/dataset_handler.hpp

Lines 69 to 71 in 9521280

	template <bool dataset_const>
	std::map<std::string, DataPointer<dataset_const>> export_dataset(Idx scenario = -1) const
	requires(dataset_const || data_mutable)

This conversion is redundant. We already have DatasetHandler which handles datasets.

Adjustments

1. Create export function in DatasetHandler to export a std::span for a single component.
2. Remove export_dataset function in DatasetHandler.
3. Change the constructor, get output, and update function of MainModel to receive range of a certain component type.
4. Create a new class OwningDataset to contain owned buffers. This can be used for the validation test and later for the serialization-to-serialization API for the C-API. (msgpack input -> msgpack output).

[mgovers]

@TonyXiang8787 how much of this is still relevant / unblocked with the new constexpr metadata from #475 ?

[TonyXiang8787]

@mgovers still quite relevant