Create table and fields for classes and structs enhancement

[AmrDeveloper]

After reading how ClangQL get function information it's time to add support for another node kind like classes,

• Find what info we can read it using libclang.
• Define the classes table with fields and fields types.
• Extend our DataProvider component to add visitors for enums.
• Update the readme file to explain table structure and add samples

Resources: https://github.com/AmrDeveloper/ClangQL/blob/master/src/clang_function_visitor.rs

https://amrdeveloper.github.io/GQL/sdk/