Async RPClient doesn't close client session #283

Describe the bug
_RPClient.__init__ sets self.own_client = False even when own Client is created, so close() doesn't close the aiohttp session.

Steps to Reproduce

from reportportal_client import ClientType, create_client

rp = create_client(ClientType.ASYNC_BATCHED, "http://localhost:8080", "project", api_key="key")
rp.create_task(rp.client.session()).blocking_result()
rp.close()
print(rp.own_client, rp.client._session)  # False <ClientSession ...>

Expected behavior
own_client is True and the session is closed.

Actual behavior
own_client is False and the session stays open (Unclosed client session exception is raised on garbage collection).

Package versions
reportportal-client 5.7.12