Merged PR 2179: Computes aggregated metrics by deal id and exposes it to reporting

This PR creates 2 new models:
- `int_core__monthly_aggregated_metrics_history_by_deal`, which just gathers the information of the previously created models that compute the kpis by deal id.
- `core__monthly_aggregated_metrics_history_by_deal`, effectively a copy from intermediate to reporting

It also includes documentation of these 2 models, differences between these and the `mtd_aggregated_metrics` equivalents and references it to exposures. I took the opportunity to update the documentation of the `core__mtd_aggregated_metrics` now that it's a bit more mature.

This should be the last PR for the first draft of 'by deal' metrics.

Related work items: #17689

models/intermediate/core/schema.yaml

@@ -143,6 +143,41 @@ models:
           - not_null
           - unique
 
+  - name: int_core__monthly_aggregated_metrics_history_by_deal
+    description: |
+      This model aggregates the monthly historic information regarding the different metrics computed
+      at deal level. The primary sources of data are the `int_core__monthly_XXXXX_history_by_deal`
+      models which contain the raw metrics data per source. 
+
+      Unlike the int_core__mtd_aggregated_metrics, this model does not abstract each metric, since
+      no comparison versus last year is performed. In short, it just gathers the information stored
+      in the abovementioned models.
+
+      To keep in mind: aggregating the information of this model will not necessarily result into
+      the int_core__mtd_aggregated metrics because 1) the mtd version contains more computing dates
+      than the by deal version, the latest being a subset of the first, and 2) the deal based model
+      enforces that a booking/guest journey/listing/etc has a host with a deal assigned, which is
+      not necessarily the case. 
+
+    tests: 
+      - dbt_utils.unique_combination_of_columns:
+          combination_of_columns:
+            - date
+            - id_deal
+
+    columns:
+      - name: date
+        data_type: date
+        description: The last day of the month or yesterday for historic metrics.
+        tests:
+          - not_null
+
+      - name: id_deal
+        data_type: character varying
+        description: Id of the deal associated to the host. 
+        tests:
+          - not_null
+
   - name: int_core__monthly_accommodation_history_by_deal
     description: |
       This model contains the historic information regarding the accommodations, also known