Add CodeGen for C++ (Libcurl)

[mohnishdeshpande]

Tell us about the task you want to perform and are unable to do so because the feature is not available
The code generation feature is missing for C++

Describe the solution/feature you'd like us to add
Add CodeGen for C++
Library - libcurl

[mohnishdeshpande]

@animator The C++ branch has also been updated (like the C codegen one) with new tests.

[ashitaprasad]

Guidelines for adding the codegen - #80