feat: add type annotations to wrapped grpc calls (#554)

* add types to grpc call wrappers

* fixed tests

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* changed type

* changed async types

* added tests

* fixed lint issues

* Update tests/asyncio/test_grpc_helpers_async.py

Co-authored-by: Anthonios Partheniou <partheniou@google.com>

* turned GrpcStream into a type alias

* added test for GrpcStream

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* added comment

* reordered types

* changed type var to P

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>