[Python] add project name to setup.py in python client (#5836)

* add project name to setup.py in python client

* update python README to use project name

* add cli option project name for python

samples/client/petstore/python/README.md

@@ -1,4 +1,4 @@
-# petstore_api
+# petstore-api
 This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
 
 This Python package is automatically generated by the [Swagger Codegen](https://github.com/swagger-api/swagger-codegen) project:

samples/client/petstore/python/setup.py

@@ -14,7 +14,7 @@
 import sys
 from setuptools import setup, find_packages
 
-NAME = "petstore_api"
+NAME = "petstore-api"
 VERSION = "1.0.0"
 # To install the library, run the following
 #