Add support for verify flag for clickhouse

[dev-cyprium]

We have a clickhouse server with a self-signed certificate and when connecting with the client we use:

clickhouse-client [...] --secure --accept-invalid-certificate

However, with datadog current implementation there isn't a way to specify this flag

no_verifyed_client = Client(
    'localhost', secure=True, verify=False
)

Pay attention to the verify flag.
Datadog library itself doesn't allow this flag: https://github.com/DataDog/integrations-core/blob/master/clickhouse/datadog_checks/clickhouse/clickhouse.py#L30

Can we please add support for it?