feat: add salary privilege to privilege management system

Add support for the salary privilege in the privilege handler. 
Implement associated logic to process and validate the 
salary privilege in the test cases. Update the data 
structures to include the new privilege and ensure 
correct functionality in the privilege processing flow.

client.go

@@ -20,6 +20,7 @@ type CompanyPrivileges struct {
 	Invoicing  bool `json:"invoicing"`
 	Accounting bool `json:"accounting"`
 	Supplier   bool `json:"supplier"`
+	Salary     bool `json:"salary"`
 }
 
 // PrivilegeHandler processes PrivilegeAdded-events and fetches the initial set of privileges from an authz-service
@@ -139,6 +140,8 @@ func (h *PrivilegeHandler) setPrivileges(email, companyId string, privilege Priv
 				c.Accounting = set
 			case PrivilegeSupplier:
 				c.Supplier = set
+			case PrivilegeSalary:
+				c.Salary = set
 			}
 		} else {
 			priv[companyId] = &CompanyPrivileges{}