Merged PR 2519: mtd bookings with 2 dimensions

# Description
This is a first idea of how I'd like to add dimensionality in the KPIs for the mtd models. For the moment, I keep deal_id apart, so I just touch the "mtd" models, that so far only contained "global" metrics.

In this case I include the listing segmentation (0, 1-5, 6-20, etc) in the bookings. To do this, I created 2 new fields: dimension and dimension_values.
I also created a "master" table with `date` - `dimension` - `dimension_value` called `int_dates_mtd_by_dimension`

Important notes:
- I force a hardcode in `int_mtd_vs_previous_year_metrics`. This is to not break production.
- You will notice how repetitive the code is starting to look. My intention with this PR is that we are happy with this approach on the naming, the strategy for joins, etc. If that's ok, next step is going to be doing macros on top. Think of the state of `int_core__mtd_booking_metrics` as the "compiled version" of the macro that should come afterwards.

# 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.
- [ ] 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: #19325

models/intermediate/core/schema.yaml

@@ -227,13 +227,34 @@ models:
       It's used for the business KPIs. Data is aggregated at the last day of the month and in the
       days necessary for the Month-to-Date computation of the current month.
 
+    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 booking-related metrics.
         tests:
           - not_null
-          - unique
+
+      - name: dimension
+        data_type: string
+        description: The dimension or granularity of the metrics.
+        tests:
+          - accepted_values:
+                values:
+                - global
+                - by_number_of_listings
+      
+      - name: dimension_value
+        data_type: string
+        description: The value or segment available for the selected dimension.
+        tests:
+          - not_null
 
   - name: int_core__mtd_guest_journey_metrics
     description: |