Create a new global instance for legacy usage of CA-based ConfigFlags. The goal is to move away from the default global instance but keep one for legacy usage (where global state is expected anyways).
The API has not changed, just a new globalConfigFlags alias is now available.
/cc @jchapman, @fwinkl, @wlampl, @christos, @mhodgkin, @jcatmore, @nstyles, @tstreble