Add Autotask Tax Region field to company edit

The customer is seeking a 'Tax Region' setting within Salesbuildr to ensure proper tax calculation and linkage with Autotask. Salesbuildr currently retrieves the tax region from the Autotask company record, and there is no dedicated field or direct management option for Autotask Tax Regions when creating companies natively in Salesbuildr. While global tax settings and company-specific quoting tax settings are available, an explicit Autotask Tax Region cannot be managed directly within Salesbuildr for newly created companies.