Merged PR 4224: Rework accounting aggregations for Financial Reporting

# Description

This PR reworks the Financial Aggregations based on Nathan's requirements, that can be found in an Excel attached to the board ticket.

Main changes:
- Accounting seed now contains 3 financial aggregations as requested by Finance
- These 3 aggregations are propagated up to reporting. This effectively breaks a WIP report - but it's WIP, not in prod, so it's not a big deal

# 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

- [X] Check if a full-refresh is required after this PR is merged. **Need to create the seed manually**

Related work items: #26618

models/reporting/xero/xero__sales_denom_mart.sql

@@ -42,6 +42,8 @@ select
     sdm.contact_name as contact_name,
     sdm.accounting_root_aggregation as accounting_root_aggregation,
     sdm.accounting_kpis_aggregation as accounting_kpis_aggregation,
-    sdm.accounting_financial_aggregation as accounting_financial_aggregation,
+    sdm.accounting_financial_l1_aggregation as accounting_financial_l1_aggregation,
+    sdm.accounting_financial_l2_aggregation as accounting_financial_l2_aggregation,
+    sdm.accounting_financial_l3_aggregation as accounting_financial_l3_aggregation,
     sdm.account_code || '-' || sdm.account_name as account_code_name
 from int_xero__sales_denom_mart sdm