Update extensions_build_config.bzl to pull in features which are not
enabled by default.
In particular, this is intended to resolve https://github.com/solo-io/gloo/issues/8968 , in which a gloo edge user was unable to enable rest EDS after upgrading to gloo edge 1.15.x/envoy-gloo 1.26.x
Introduces a script to check that the extensions_build_config.bzl is up to date with the current envoy version.
This script is run as a github action on every PR to ensure that the extensions_build_config.bzl is up to date with the current envoy version.
Description