CPP Header autogeneration for integrated monomer templates

**Background**
#1412 Introdoced hardcoded basic monomer templates for phosphates, nucleobases and sugars.
The template data saved here: https://github.com/epam/Indigo/blob/master/core/indigo-core/molecule/monomers_basic_templates.h
This file is inconvenient to edit and add new monomer templates.

**Solution**
Monomer's templates should be stored in regular .KET file like monomers_basic_templates.ket and corresponding monomers_basic_templates.h should be autogenerated with cmake.

Start by reading core/indigo-core/molecule/monomers_basic_templates.h and the surrounding CMake configuration. Define the regular monomers_basic_templates.ket source and determine how CMake should generate the corresponding header. Done means the templates are maintained in the KET file, the header is generated from it, and the project still builds successfully.

Written by the indexing model from the issue text.