ODOO-236: Port MultiSafepay Cloud POS integration to Odoo 19

[zulquer]

This Pull Request ports and adapts the MultiSafepay Cloud POS integration module for compatibility with Odoo 19.0.
It consists of two main parts:

1. Importing the core Cloud POS integration feature code as implemented in Odoo 18.
2. Applying critical compatibility adjustments, schema fixes, and linting corrections required by Odoo 19's stricter architecture.

1. Core Feature Port (Odoo 18 codebase base)

• Re-implemented frontend payment terminal connection, polling logic, and error handling.
• Re-implemented transaction status synchronizations (reversals, cancellations, and refunds).

2. Odoo 19.0 Compatibility & Fixes

• Missing Field Fix on pos.payment: Added the missing msp_cloud_refund_source_order_id field on the pos.payment model and loaded it into the POS UI cache (_load_pos_data_fields). This resolves a crash on Odoo 19's frontend validation when triggering refunds (line.update() fails in Odoo 19 if fields are not defined on the Python model).
• Setup Data Upgrades: Marked demo/setup journals with noupdate="1" in data.xml to prevent Odoo's registry validator from failing when trying to rewrite active payment method journals during module upgrades.
• Code Style & ESLint Fixes: Resolved ESLint issues (specifically no-unused-vars for tipProductId and no-shadow on the line variable inside sendPaymentCancel) to ensure all pre-commit hooks pass successfully.