Add cluster.waitUntilReady method to Node.js SDK to handle GCCCP initialization gracefully

[nmdaniil]

Please consider adding a waitUntilReady method to the Node.js SDK, similar to the Java SDK.
Currently, there is no native way to wait for the cluster to fully initialize, often causing the following warning at startup:

[warn] unable to find connected session with GCCCP support, retry in 2500ms

[thejcfactor]

Hi @nmdaniil -- This is a fair request. I have created JSCBC-1321 in our JIRA tracking system. I imagine we can address this feature request in the somewhat near future but TBD on when it will actually drop. I will update this GH issue as more details come to light.