Add docs and integration test for native asyncpg connection pool #382
Description
Port of GoogleCloudPlatform/cloud-sql-python-connector#1180, we should update async usage guide of README to showcase both SQLAlchemy connection pool and native asyncpg connection pool.
Description
As of asyncpg v0.30.0 it is now possible to pass a custom connection function into the
asyncpg.create_poolmethod, which means it is now possible to use the cloudsql connector without SQLAlchemy, thus maintaining the original API of the asyncpg pool (which is rather important if you are migrating an existing codebase that made heavy use of an asyncpg pool).Might be helpful to future readers of the docs to reflect that here.
cc @d1manson who contributed this awesome feature to asyncpg 👏