Expand `load_diet_composition()` to support Ecosim consumption files

[Bai-Li-NOAA]

Update the load_diet_composition() function so it can handle input from 'consumption-biomass_annual.csv' and 'consumption-biomass_monthly' files generated by EwE Ecosim models. This will improve compatibility and allow users to work with data exported from EwE Ecosim directly.

Acceptance Criteria:

• Function correctly loads and parses both file types
• Add tests for annual and monthly consumption-biomass files
• Update documentation and example usage