Merged PR 4572: Applies logic to modify the invoicing cycle date depending on the issuing source

# Description

Hyperline invoices/credit notes have an issuing date that corresponds to the moment in which these are actually created.

This is an issue since it means that an invoice or credit note posted today, 4th March 2025, that is supposed to be related to February 2025 invoicing cycle, will have:

* If the document is posted in Hyperline, an issuing date on the March 2025
* If the document is NOT posted in Hyperline, an issuing date on February 2025

This PR just creates a field that handles the logic effectively, to be used further in other reports/kpis purposes.

# 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: #28158

models/reporting/xero/xero__sales_denom_mart.sql

@@ -25,6 +25,8 @@ select
     sdm.document_number as document_number,
     sdm.document_issued_at_utc as document_issued_at_utc,
     sdm.document_issued_date_utc as document_issued_date_utc,
+    sdm.document_is_effective_at_end_of_month_utc
+    as document_is_effective_at_end_of_month_utc,
     sdm.document_type as document_type,
     sdm.document_currency_iso_4217 as document_currency_iso_4217,
     sdm.exchange_rate_to_gbp as exchange_rate_to_gbp,