Small refactorings to fix CLI import errors for replicator

[whummer]

Small refactorings to fix CLI import errors for replicator. This was detected in a debugging session together with @robertlcx , where we saw a couple of errors related to importing the CLI code from Python 3.9.

...
  File "/Users/localstack/SynologyDrive/repos/localstack-snowflake-samples/airflow-dbt-transformation/.venv/lib/python3.9/site-packages/localstack/aws/protocol/parser.py", line 1047, in VirtualHostRewriter
    def _is_vhost_address_get_bucket(request: Request) -> str | None:
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

...

  File "/Users/localstack/SynologyDrive/repos/localstack-snowflake-samples/airflow-dbt-transformation/.venv/lib/python3.9/site-packages/localstack/services/cloudformation/service_models.py", line 27, in <module>
    class GenericBaseModel:
  File "/Users/localstack/SynologyDrive/repos/localstack-snowflake-samples/airflow-dbt-transformation/.venv/lib/python3.9/site-packages/localstack/services/cloudformation/service_models.py", line 110, in GenericBaseModel
    def physical_resource_id(self) -> str | None:
TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

...

  File "/Users/localstack/SynologyDrive/repos/localstack-snowflake-samples/airflow-dbt-transformation/.venv/lib/python3.9/site-packages/rolo/websocket/websocket.py", line 10, in <module>
    from rolo.asgi import ASGIWebSocket, WebSocketEnvironment, WebSocketListener
  File "/Users/localstack/SynologyDrive/repos/localstack-snowflake-samples/airflow-dbt-transformation/.venv/lib/python3.9/site-packages/rolo/asgi.py", line 46, in <module>
    WebSocketEnvironment: t.TypeAlias = t.Dict[str, t.Any]
AttributeError: module 'typing' has no attribute 'TypeAlias'

In this PR we're removing a couple of imports or try to defer them to later stages, to be able to run the replicator proxy from the CLI (in container mode) via:

$ localstack aws proxy --container -s s3
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