Issue 1714: fix validation for locator name

[Iogsotot]

• [Medium] Если на странице есть одинаковые элементы, то такой объект нельзя отредактировать  #1714

Refactoring and Code Improvements

• Fixed variable and function names for better clarity.
• Added types to improve type safety.
• Corrected typos in the code.
• Added comments for better understanding of the code.

Testing

• Aligned test names and code style with overall coding standards.

Feature Re-enablement

• Re-enabled CSS selector calculation and template download features relevant to the local back-end.

New Features and Enhancements

• Introduced custom validation to handle visible and invisible elements.
• Improved code style and naming conventions for better readability and maintainability.