Add SimCalorimeterPulse data type for storing simulated calorimeter pulses pre-digitization

[sly2j]

Briefly, what does this PR introduce?

This PR adds a new data type, edm4eic::SimCalorimeterPulse, to represent simulated calorimeter pulses before digitization.

The new structure is modeled consistently with edm4hep::SimCalorimeterHit and aligns with existing waveform structures such as edm4hep::RawTimeSeries (generic digitization output) and edm4hep::TimeSeries (generic measured time series).

SimCalorimeterPulse defines three one-to-many relations relations:

• SimCalorimeterHit: Pulses can be constructed from contributions of one or more simulated calorimeter hits.
• SimCalorimeterPulse: Pulses can be constructed out of other pulses.
• MCParticle: Each pulse can be attributed to a single MCParticle (primary pulse), multiple MCParticles (overlayed pulses), or zero MCParticles (noise pulse).

Storing calorimeter pulses at the simulation level ensures conceptual clarity and consistency within our data model. The simulated pulse data to be stored in this structure have no equivalent in real detector output, and are therefore not digitization output.

By using a Simulation structure, we gain direct Relation support with other simulation entities, enabling efficient backward navigation through the simulation chain. While Associations are used to link digitization and reconstruction structures to simulation, Relations are preferred for internal connections within the same domain (e.g. within Simulation or within Reconstruction). This design avoids introducing redundant Association types and keeps the data model consistent, clean and efficient.

What kind of change does this PR introduce?

• Bug fix (issue #__)
• New feature (issue #__)
• Documentation update
• Other: __

Please check if this PR fulfills the following:

• Tests for the changes have been added
• Documentation has been added / updated
• Changes have been communicated to collaborators

Does this PR introduce breaking changes? What changes might users need to make to their code?

No

Does this PR change default behavior?

No