Report locale updates (#12208)

* Optional 'locale' arg to format_money

- Allows override of system locale when generating reports

* Updated documentation

* Add unit tests

* Handle invalid locale

* Handle invalid locale

* Add new global setting to control currency locale in reports

* Use setting in reports

* Add CHANGELOG entry

* Further unit tests

* Add unit tests for new setting

* Update docs

* More docs

* Refactoring:

- Change REPORT_CURRENCY_LOCALE to REPORT_LOCALE

* Extend unit testing

* Refactor format_number

* Add unit tests for explicit format strings

* Update examples for format_date

* Updated unit  tests

* Cleanup unit tests

* Fix more tests

* Adjust wording

* Remove global setting - simplify code

* Simplify unit tests

* Revert 'min_digits' to 'leading'

* Fix docs

* Refactor the render_currency function

- Move all functionality into report.py

* Cleanup duplicate code

* Updated docs

* Allow user to specify date_format

* Add support for 'leading' digits in render_currency

* Bug fix

* Fix unit test

* Add tests for "include_symbol"

docs/docs/concepts/pricing.md

@@ -63,3 +63,9 @@ Currency exchange rates are updated periodically, using the configured currency
 ## Pricing Settings
 
 Refer to the [global settings](../settings/global.md#pricing-and-currency) documentation for more information on available currency settings.
+
+## Rendering Currencies in Reports
+
+Currency values can be rendered in report templates using the [`render_currency`](../report/helpers.md#render_currency) helper function. This function formats a currency amount according to a locale, and supports currency conversion within the template.
+
+See the [report helpers documentation](../report/helpers.md#currency-formatting) for full details and examples.