Bring back dataset as a required field for BigQuery profile

In PR #1017, we attempted to remove `dataset` from the required
fields list for the BigQuery profile. However, we realised that
this is failing BiqQuery dbt operations as it indeed is a required
field. Hence, bring back the same as a required field. This is
also necessary for building the mock profile where we construct
the profile by taking in consideration only the required fields.

closes: #1031

cosmos/profiles/bigquery/service_account_keyfile_dict.py

@@ -20,8 +20,11 @@ class GoogleCloudServiceAccountDictProfileMapping(BaseProfileMapping):
     dbt_profile_type: str = "bigquery"
     dbt_profile_method: str = "service-account-json"
 
+    # Do not remove dataset as a required field form the below list. Although it's observed that it's not a required
+    # field for some databases like Postgres, it's required for BigQuery.
     required_fields = [
         "project",
+        "dataset",
         "keyfile_json",
     ]
 

tests/profiles/bigquery/test_bq_service_account_keyfile_dict.py

@@ -96,6 +96,7 @@ def test_mock_profile(mock_bigquery_conn_with_dict: Connection):
         "type": "bigquery",
         "method": "service-account-json",
         "project": "mock_value",
+        "dataset": "mock_value",
         "threads": 1,
         "keyfile_json": None,
     }