Merged PR 3756: First version of verification request feature flag

# Description

Brings VerificationRequestFeatureFlag to staging. Needs further modelling to clean data for A/B test tracking purposes, but this will be done in intermediate.

# 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: #25145

models/staging/core/_core_sources.yml

@@ -261,3 +261,5 @@ sources:
         identifier: ProductProtectionPlanBillingItem
       - name: ProductServiceBillingItem
         identifier: ProductServiceBillingItem
+      - name: VerificationRequestFeatureFlag
+        identifier: VerificationRequestFeatureFlag

models/staging/core/schema.yml

@@ -1281,3 +1281,80 @@ models:
         data_type: timestamp
         description: |
           Timestamp of when this record was extracted into DWH.
+
+  - name: stg_core__verification_request_feature_flag
+    description: |
+      Provides the Feature Flag and the variation a given Verification Request is in. 
+      Mostly used for A/B test tracking purposes on the scope of the Guest Journey.
+
+    columns:
+      - name: id_verification_request_feature_flag
+        data_type: integer
+        description: |
+          Identifier of the Verification Request Feature Flag. Acts as the primary key for this table.
+        tests:
+          - unique
+          - not_null
+
+      - name: id_verification_request
+        data_type: integer
+        description: |
+          Identifier of the Verification Request. Acts as foreign key to the Verification Request table.
+          It can be duplicated across different Feature Flags - meaning the same verification request 
+          can be part of none, one, or several A/B tests.
+        tests:
+          - not_null
+
+      - name: feature_flag_name
+        data_type: string
+        description: |
+          Name of the Feature Flag, or the Guest Journey A/B test. Cannot be null.
+        tests:
+          - not_null
+
+      - name: feature_flag_variation
+        data_type: string
+        description: |
+          Identifier of the variation a given Verification Request is in, within a
+          given Feature Flag, or Guest Journey A/B test. It can be null.
+
+      - name: is_feature_flag_enabled
+        data_type: boolean
+        description: |
+          Identifies whether the feature flag was enabled or disabled. In other words,
+          if the A/B test was active or not. In these cases, the feature flag variation 
+          of the Guest Journeys would receive the default variation value (the control 
+          group, generally speaking).
+
+      - name: created_at_utc
+        data_type: timestamp
+        description: |
+          Timestamp of when this Verification Request Feature Flag record was created.
+        tests:
+          - not_null
+
+      - name: created_date_utc
+        data_type: date
+        description: |
+          Date of when this Verification Request Feature Flag record was created.
+        tests:
+          - not_null
+
+      - name: updated_at_utc
+        data_type: timestamp
+        description: |
+          Timestamp of when this Verification Request Feature Flag record was last updated.
+        tests:
+          - not_null
+
+      - name: updated_date_utc
+        data_type: date
+        description: |
+          Date of when this Verification Request Feature Flag record was last updated.
+        tests:
+          - not_null
+
+      - name: dwh_extracted_at_utc
+        data_type: timestamp
+        description: |
+          Timestamp of when this Verification Request Feature Flag record was extracted into DWH.

models/staging/core/stg_core__verification_request_feature_flag.sql

@@ -0,0 +1,33 @@
+{{
+    config(
+        materialized="incremental",
+        unique_key="id_verification_request_feature_flag",
+    )
+}}
+
+
+with
+    raw_verification_request_feature_flag as (
+        select * from {{ source("core", "VerificationRequestFeatureFlag") }}
+    ),
+    stg_core__verification_request_feature_flag as (
+        select
+            {{ adapter.quote("Id") }} as id_verification_request_feature_flag,
+            {{ adapter.quote("VerificationRequestId") }} as id_verification_request,
+            {{ adapter.quote("Name") }} as feature_flag_name,
+            {{ adapter.quote("State") }} as feature_flag_variation,
+            {{ adapter.quote("IsEnabled") }} as is_feature_flag_enabled,
+            {{ adapter.quote("CreatedDate") }} as created_at_utc,
+            cast({{ adapter.quote("CreatedDate") }} as date) as created_date_utc,
+            {{ adapter.quote("UpdatedDate") }} as updated_at_utc,
+            cast({{ adapter.quote("UpdatedDate") }} as date) as updated_date_utc,
+            {{ adapter.quote("_airbyte_extracted_at") }} as dwh_extracted_at_utc
+        from raw_verification_request_feature_flag
+    )
+select *
+from stg_core__verification_request_feature_flag
+{% if is_incremental() %}
+    where
+        updated_at_utc
+        >= ((select max(updated_at_utc) from {{ this }}) - interval '7 days')
+{% endif %}