Update how ClusterOptions and connection string query params parsed

Currently the Python SDK will merge the parsing of ClusterOptions and the connection string query parameters. If there is an unknown parameter (i.e. one that does not match the allowed keys for ClusterOptions) that parameter is ignored. We should make a handful of small updates:

• Provide a parameter, 'allow_unknown_qstr_options' that will allow unknown query string params to pass through to the C++ SDK for parsing of the connection string.
• Utilize the changes from CXXCBC-326 to raise warnings after calling `couchbase::core::utils::parse_connection_string()` (see code here)
• Determine when we should raise an error versus raising a warning. Currently when we parse ClusterOptions/connection string query params we will raise exceptions if the value is invalid, it is possible we want to move to logging a warning for some of these instances. Could also just parse the option(s), pass through to the C++ SDK and lean on how it parses the options.