Fix property name usage in error messages of rules in `Nested` rule

[vjik]

Q	A
Is bugfix?	✔️
New feature?	❌
Breaks BC?	❌
Fixed issues	#631

[what-the-diff[bot]]

PR Summary

• Improved Clarity on Error Messages A bug fix was introduced to improve error messages related to rules in the Nested rule. This helps users better understand and rectify the issues signalled by these messages.

• Streamlined System Resource Usage The implementation of an ignoreFiles option means that the system will skip scanning the vendor directory during its operations. This can significantly save system resources and improve efficiency.

• Enhanced Attribute Validation for Nested Structures Changes were made to the NestedHandler.php file that upgrade the way the system validates attributes in nested structures. This will improve the accuracy of the system's operations.

• Improved Test Coverage The NestedTest.php file was updated to include new tests specifically designed for error messages dealing with attributes in nested structures. This ensures that our code is well-tested and reliable.