[CLI] Add option to suppress certificate validation

[pcholakov]

The restate utility should be able to connect to HTTPS endpoints while disregarding certificate validity when only encryption is required, similar to curl's -k / --insecure argument.

Sometimes it's desirable to have TLS even if certificate validation isn't enforced. E.g. Restate's
CDK SingleNodeDeployment construct creates a restate public endpoint reachable over the internet that uses a self-signed certificate out of the box.