[python-pydantic-v1] various improvements (#16658)

* rename, add tests

* remove library support in python pydantic v1 codegen

* copy tests

* copy echo api tests

* update samples

* update doc

* add back library support

samples/openapi3/client/petstore/python-pydantic-v1-aiohttp/tests/util.py

@@ -0,0 +1,19 @@
+# flake8: noqa
+
+import asyncio
+import random
+
+
+def id_gen(bits=32):
+    """ Returns a n-bit randomly generated int """
+    return int(random.getrandbits(bits))
+
+
+def async_test(f):
+    def wrapper(*args, **kwargs):
+        # coro = asyncio.coroutine(f)
+        coro = f
+        future = coro(*args, **kwargs)
+        loop = asyncio.get_event_loop()
+        loop.run_until_complete(future)
+    return wrapper