Replace PostgreSQL parser to libpg_query wrapper

[SoftStoneDevelop]

• Create native nuget for libpg_query #22.
• Create wrapper in two versions .net standart 2.0 for generator and .net 7 for another cases #23
• Replace PostgreSQL parser to libpg_query .net parser #24

This is start for create nuget(https://digitalhouseblog.wordpress.com/2019/08/22/how-to-make-a-nuget-package-for-c/).
This change improve nuget experience. Same parser like in postgre server. This means we can get return aliases in all cases(return, subquery, func).