Make HazelcastClient context manager aware (PEP-343)

Sorry, if the issue like this was opened before, I've searched but not found it.

Is it possible to make a `HazelcastClient` conext manager aware, see https://peps.python.org/pep-0343/

In short:

To be able instead of:

```python
client = hazelcast.HazelcastClient(...)
# operations
client.shutdown()
```

make calls like this:
```python
with hazelcast.HazelcastClient(...) as client:
# operatoins...
# no need to call client.shutdown() - it will be called by context manager
```

May be there are some other classes that could be also made context manager aware.

Thanks!