Thai Localization - Tier Department Level

This module adds department-based approval levels on top of the tier validation system. On each department form you get a new "Approval Level" section where you can list approvers in order, each with a description and a sequence that determines the level number.

• The level number is calculated automatically from the order of the lines, so the first line is level 1, the second is level 2, and so on.
• Each level must have an approver (a user); the company is filled in automatically and is only shown when multi-company is enabled.
• A separate "Tier Level" screen (list and form) lets you view and manage these approval levels, with a dedicated access group "Manage Approval Levels" for creating, editing and deleting them; ordinary users can only read them.
• The module also adds an "Allow Restart Validation" group. Only users in that group see the restart validation button on tier validation documents, and clicking it asks for confirmation because the action cannot be undone. System administrators automatically receive both groups.

It extends the HR department model (hr.department) and introduces a new tier.level model, and it relies on the tier validation formula module to pick the reviewer for a given level.