Adds localized accounting reports for Sri Lanka, including balance sheet and profit and loss reporting. This helps Sri Lankan businesses use Odoo with reports aligned to local accounting needs and improves report structure and balancing.

Implement a basic accounting package for Sri Lanka including:

- COA
- Tax groups
- Taxes
- Fiscal Positions
- Tax reports (VAT001, WHT001)

task-4352802

retargeted from master #224917