feat: add nix files needed for cpp code auto generation

[Khushboo-dev-cpp]

adding cpp generator for this module
and also aligning the nix files as done with standard modules
rename liblogos-blockchain-module to liblogos_blockchain_module
so that the cpp autogenerated files are with underscore with hyphen because C++ identifiers cannot contain hyphens

[strinnityk]

I have a few questions regarding the whole splitting thing but let's address them in order:

• Why split the include and lib packaging?
• Why are we overriding flake's cmake integration and specifying the commands manually?

[strinnityk]

Why are we calling this default if this is just providing common definitions? We are even assigning it to a variable called common below.

[Khushboo-dev-cpp]

I guess we could call it common.nix too? I kind of kept the name consistent with other modules.

[Khushboo-dev-cpp]

I have a few questions regarding the whole splitting thing but let's address them in order:

• Why split the include and lib packaging?

The reason this is split is because the lib is to call Cmake to build the lib and include for calling the cpp-generator and generating headers. The cpp generator helps call cross module calls and hence Ive added the support to it.

• Why are we overriding flake's cmake integration and specifying the commands manually?

hmm I think you are right, I am going to dive in and look at the CmakeLists.txt and again and check if we can remove the redundant parts.