Distinguish between python package for generator and generated code

[ashutshkumr]

• Put generator dependencies in requirements.txt or setup.py
• setup.py currently present in project dir should identify package snappi-gen and not snappi itself
• New setup.py should be generated (or duplicated from existing), which should be called snappi and include dependecies for generated code
• Generated code should be copied to be a separate directory (and hence snappicommon.py + other existing files should be copied to dir containing generated code)
• Generated code should also include .yaml or .json spec

#1 and #2 are subject to further discussion (if separate snappi-gen package is not desired).

[Rangababu-R]

all are addressed by openapiart and this issue is no more valid