Changing naming to follow convention.
This PR has the following changes:
- the model `int_core__mtd_aggregated_metrics` has been moved to cross and changed the name to `int_mtd_aggregated_metrics`
- the model `int_core__monthly_aggregated_metrics_history_by_deal` has been moved to cross and changed the name to `int_monthly_aggregated_metrics_history_by_deal`
- the reporting models `core__mtd_aggregated_metrics` and `core__monthly_aggregated_metrics_history_by_deal` now source the `int_mtd_aggregated_metrics` and `int_monthly_aggregated_metrics_history_by_deal` to avoid breaking the production dashboard
- the reporting models have been duplicated from core into general with the correct names, i.e., `mtd_aggregated_metrics` and `monthly_aggregated_metrics_history_by_deal`
- Documentation has been moved in intermediate and replicated in reporting, adding comments on the currently in use models that are going to die soon.
This will allow for a transition of the PBI dashboard from one source to another. Exposures file still not touched since technically the report is still sourcing the 'legacy' models. Documentation of the refactor here: https://www.notion.so/knowyourguest-superhog/Refactoring-Business-KPIs-5deb6aadddb34884ae90339402ac16e3
Related work items: #18202
