Merged PR 3169: Adding Churn metrics to Global KPIs

# Description

Main changes:
- Creation of `int_monthly_churn_metrics` model. This follows a similar approach as for mtd models, with jinja loops to aggregate the metrics at different dimensions. This reads from the previous monthly model, thus creating a dependency on Global KPIs with By Deal KPIs.
- Adds the 6 metrics in the main aggregated model of Global KPIs `int_mtd_vs_previous_year_metrics`. It doesn't necessarily mean that the 6 metrics will be made available in the report.

This does NOT display these metrics in the report, and won't be done until deal lifecycle is enriched to consider hubspot offboarding in the state "05-Churning".

# Checklist

- [X] The edited models and dependants run properly with production data.
- [X] The edited models are sufficiently documented.
- [X] The edited models contain PK tests, and I've ran and passed them.
- [X] I have checked for DRY opportunities with other models and docs.
- [X] I've picked the right materialization for the affected models.

# Other

- [ ] Check if a full-refresh is required after this PR is merged.

Related work items: #22691

models/intermediate/cross/schema.yml

@@ -1262,3 +1262,83 @@ models:
               min_value: 0
               max_value: 1
               strictly: false
+
+  - name: int_monthly_churn_metrics
+    description: |
+      This model is used for global KPIs.
+
+      It computes the churn contribution by dimension, dimension value 
+      and date, in a monthly basis. This model is different from the 
+      usual mtd ones since it strictly depends on the monthly computation 
+      of metrics by deal, which is done in a monthly basis rather than mtd. 
+      In essence, it means we won't have data for the current month. 
+
+      This model retrieves the 12 month contribution to global metrics 
+      by deal and aggregates it to dimension and dimension value for those 
+      deals that are tagged as '05-Churning' in that month. Thus, it provides 
+      a total of 6 churn related metrics, represented as ratios over the total:
+      - Total Revenue (in GBP)
+      - Created Bookings 
+      - Listings Booked in Month 
+      In two ways of computing the contribution, Additive and Average. For further 
+      information, please refer to the documentation of the model: 
+      - int_monthly_12m_window_contribution_by_deal
+
+      Lastly, when checking data at any dimension distinct from Global, at the 
+      moment these values represent the additive contribution of churn with respect 
+      to the global amount. This means that, for instance, if we have 10% of churn 
+      in a month, it can be divided by 9% USA and 1% GBR since 9%+1% = 10%.
+
+    tests:
+      - dbt_utils.unique_combination_of_columns:
+          combination_of_columns:
+            - date
+            - dimension
+            - dimension_value
+
+    columns:
+      - name: date
+        data_type: date
+        description: The date for the month-to-date metrics.
+        tests:
+          - not_null
+
+      - name: dimension
+        data_type: string
+        description: The dimension or granularity of the metrics.
+        tests:
+          - accepted_values:
+              values:
+                - global
+                - by_number_of_listings
+                - by_billing_country
+
+      - name: dimension_value
+        data_type: string
+        description: The value or segment available for the selected dimension.
+        tests:
+          - not_null
+
+      - name: total_revenue_churn_additive_contribution
+        data_type: numeric
+        description: Total Revenue churn rate (additive approach).
+
+      - name: created_bookings_churn_additive_contribution
+        data_type: numeric
+        description: Created Bookings churn rate (additive approach).
+
+      - name: listings_booked_in_month_churn_additive_contribution
+        data_type: numeric
+        description: Listings Booked in Month churn rate (additive approach).
+
+      - name: total_revenue_churn_average_contribution
+        data_type: numeric
+        description: Total Revenue churn rate (average approach).
+
+      - name: created_bookings_churn_average_contribution
+        data_type: numeric
+        description: Created Bookings churn rate (average approach).
+
+      - name: listings_booked_in_month_churn_average_contribution
+        data_type: numeric
+        description: Listings Booked in Month churn rate (average approach).