Atomic updates of xDS resources with their dependencies

When the pilot crashes, in some scenarios, the configuration data will be inconsistent, resulting in a request of 503 NR~ （https://github.com/istio/istio/issues/25495）

Ads is the final consistency, but in the process of ads pushing, if pilot crash, it will cause abnormal traffic, such as after pushing cds and then the process crash~

It is recommended whether ads (rds, eds, lds, rds) can be accompanied by a version number, and cds can be associated with lds and rds, so that the configuration will take effect only after all configurations are correctly received, and the configuration will be in the warm state before the configuration takes effect.

@htuch @lizan