Merged PR 2003: Business KPIs first draft

This PR aims to provide a first draft for business KPIs, at this stage **quite minimal**.

It mostly contains a MTD and Monthly display approach. No dimensions are created.

The models created are:
- **int_dates_mtd**: mainly it reads from int_dates to retrieve those days needed for a MTD/monthly display
- **int_core__mtd_booking_metrics**: it contains the booking metrics, ending in a format of date|value|value last year|increment
--> here we could add, in the future, additional metrics from other sources (ex: guest journey, etc)
- **int_core__mtd_aggregated_metrics**: it transforms the data coming from the different mtd intermediate sources to be easily displayed in the dashboard. This is a good candidate for macros :)
- **core__mtd_aggregated_metrics**: copy-paste of the its int_core version, including a bit of model documentation

The dashboard is functional but in another PR. I can show you how it looks like at the moment you are going to check the PR

Related work items: #17214

models/intermediate/core/schema.yaml

@@ -143,3 +143,70 @@ models:
           - not_null
           - unique
 
+  - name: int_core__mtd_booking_metrics
+    columns:
+      - name: date
+        data_type: date
+        description: The date for the month-to-date booking-related metrics.
+        tests:
+          - not_null
+          - unique
+
+  - name: int_core__mtd_aggregated_metrics
+    description: |
+      The `int_core__mtd_aggregated_metrics` model aggregates multiple metrics on a year, month, and day basis. 
+      The primary sources of data are the `int_core__mtd_XXXXX_metrics` models, which contain the raw metrics data per source. 
+      This model uses Jinja templating to dynamically generate SQL code, combining various metrics into a single table. 
+      This approach reduces repetition and enhances maintainability.
+    tests: 
+      - dbt_utils.unique_combination_of_columns:
+          combination_of_columns:
+            - date
+            - metric
+            
+    columns:
+      - name: year
+        data_type: int
+        description: year number of the given date.
+        tests:
+          - not_null
+
+      - name: month
+        data_type: int 
+        description: month number of the given date.
+        tests:
+          - not_null
+
+      - name: day
+        data_type: int
+        description: day monthly number of the given date.
+        tests:
+          - not_null
+
+      - name: is_end_of_month
+        data_type: boolean
+        description: is end of month, 1 for yes, 0 for no.
+        tests:
+          - not_null
+
+      - name: is_current_month
+        data_type: boolean
+        description: |
+          checks if the date is within the current executed month, 
+          1 for yes, 0 for no.
+        tests:
+          - not_null
+
+      - name: date
+        data_type: date
+        description: |
+          main date for the computation, that is used for filters. 
+          It comes from int_dates_mtd logic.
+        tests:
+          - not_null
+
+      - name: metric
+        data_type: text
+        description: name of the business metric.
+        tests:
+          - not_null