[ENHANCEMENT] Implement infrared spectrum calculation for bulk systems

**Is your feature request related to a problem? Please describe.**
At the moment MDANSE can calculate an infrared spectrum by considering dipole moments of individual molecules. There is no equivalent implementation for trajectories where molecules are not defined.

**Describe the solution you'd like**
An alternative setting and corresponding calculation needs to be added to the code to allow the calculation of infrared spectra for bulk systems.

**Describe alternatives you've considered**
N/A

**Additional context**
Correctness of the results will need to be verified.

Start by locating the existing infrared-spectrum calculation that uses dipole moments of individual molecules, then trace how trajectory settings and calculations are exposed. Define the bulk-system alternative and identify how its results can be verified for correctness; the issue names no files or tests.

Written by the indexing model from the issue text.