feat: add attributes to createCustomer function

This commit includes enhancements in customer creation feature. Specifically, it modifies the createCustomer function by adding a new parameter $attributes to handle attribute data during customer creation process. Moreover, it introduces UI components to collect these attribute details. Updates have been made to the associated form elements, button actions and display methods to accommodate these changes. In addition, it makes considerable changes in the backend JavaScript files to facilitate frontend changes and to meet compatibility.

There's also a change in error handling part where it replaces the try-catch block, which attempt to get the standard address, with direct command. This assures the retrieval of the standard address, if exists, else a new address will be created implicitly.

Finally, few general code improvements are done like changing usage of var to const or let where necessary for better maintainability. A minor adjustment on window height property is also made in CustomerWindow.js file.

Related: #68 (closed)