[Python] Support for per-operation servers (#6557)

* Dynamic server support

* regenerated

* Apply suggestions from code review

Co-authored-by: Thomas Hervé <thomas.herve@datadoghq.com>

* regenerated

* Add ParameterizedServer feature to Python experimental

* Fix lookup of server variables

* Add tests and change default value for servers

* Fix server variables

* Return base path when index is None

* Use HOST

* Apply suggestions from code review

* Apply suggestions from code review

* regenerated

* Add specific tests for dynamic servers

* regenerated

* add docstring

* regenerated

* Fix wrong merge resolution

Co-authored-by: Thomas Hervé <thomas.herve@datadoghq.com>

samples/openapi3/client/features/dynamic-servers/python-experimental/setup.py

@@ -0,0 +1,49 @@
+# coding: utf-8
+
+"""
+    OpenAPI Extension with dynamic servers
+
+    This specification shows how to use dynamic servers.  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+from setuptools import setup, find_packages  # noqa: H301
+
+NAME = "dynamic-servers"
+VERSION = "1.0.0"
+# To install the library, run the following
+#
+# python setup.py install
+#
+# prerequisite: setuptools
+# http://pypi.python.org/pypi/setuptools
+
+REQUIRES = [
+  "urllib3 >= 1.15",
+  "six >= 1.10",
+  "certifi",
+  "python-dateutil",
+  "nulltype",
+]
+EXTRAS = {':python_version <= "2.7"': ['future']}
+
+setup(
+    name=NAME,
+    version=VERSION,
+    description="OpenAPI Extension with dynamic servers",
+    author="OpenAPI Generator community",
+    author_email="team@openapitools.org",
+    url="",
+    keywords=["OpenAPI", "OpenAPI-Generator", "OpenAPI Extension with dynamic servers"],
+    install_requires=REQUIRES,
+    extras_require=EXTRAS,
+    packages=find_packages(exclude=["test", "tests"]),
+    include_package_data=True,
+    license="Apache-2.0",
+    long_description="""\
+    This specification shows how to use dynamic servers.  # noqa: E501
+    """
+)