python: generate Pydantic v2 + typing complete code (#16624)

* python: improve type generation with more specific typing

* Annotate function parameters

* Remove unused imports

* remove unused files

* remove temporary hack

* remove lock file

* fix Annotated import

* support Python 3.7

* Regenerate code with typing-extensions

* Fix setup.py

* More Pydantic v2 compatibility

* depend on pydantic v2

* fix client_echo tests

* fix JSON serialization

* Fix references

* Skip circular dependency tests for now

* Temporarily hide the "float" property

The "float" property aliases the "float" type and completely breaks the
model: all the properties that were "float" now become the type of the
"float" property instead.

* Fix errors

* Import Literal from typing_extensions

* Fix GitHub Action workflows

* Fix Python 3.7 failure

* Fix quotes

* Apply suggestions from code review

* Fix tests

* split model imports from other modules imports

* fix workflow

* Comment the array unique items convertion, remove set translation

* Replace alias usage

.github/workflows/samples-python-pydantic-v1-client-echo-api.yaml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         sample:
           # clients
-          - samples/client/echo_api/python
+          - samples/client/echo_api/python-pydantic-v1/
         python-version:
           - "3.7"
           - "3.8"