* Import @com_lyft_protoc_gen_validate for validate.proto annotations.
* Example annotation in address.proto (BindConfig).
* Process optional/required annotations in protodoc.
Signed-off-by: Harvey Tuch <htuch@google.com>
This PR follows thru on https://github.com/envoyproxy/envoy/issues/1873
on the data-plane-api side.
Also, update the Python validation script and added a test to ensure
this is captured in CI to avoid future bit rot.
Signed-off-by: Harvey Tuch <htuch@google.com>