[v4integration] Introduce NODE_CTX_* macros

The aim is to minimise amount of duplicated code. It's not a final
version, and macros can be changed or even removed.
[buffer] Make use of NODE_CTX_* macros
[fs,path,process,util] Make use of NODE_CTX_* macros
[globalextensions] Make use of NODE_CTX_* macros
[module] Make use of NODE_CTX_* macros
[console] Make use of NODE_CTX_* macros
[engine] Make use of NODE_CTX_* macros