[18.0][MIG] hr_timesheet_portal: Migration to 18.0

[innovara]

This migration follows the recent migration of hr_timesheet_portal to 17.0. There is already OCA/timesheet#800 for 18.0, but that one is more of a direct drop-in of code that works in 18.0, whereas this PR includes the full commit history and therefore provides traceability of the changes. However, the contribution of its author is acknowledged, as they were added to the list of contributors in the migration to 17.0.

Speaking of which:

hr_timesheet_portal/static/src/js/hr_timesheet_portal.esm.js

• Replaced session and bound user service with a static user import.
• Used browser.setTimeout instead of the global setTimeout to satisfy ESLint.
• Removed legacy this.user binding and unused imports.

hr_timesheet_portal/templates/portal.xml

• Replaced analytic_account_id with account_id.

@hbrunn once again, would you be so kind to review it for me please?