Migrate Flight and FlightSql Proto Gen

[joellubi]

Flight and FlightSql definitions are still in apache/arrow.

The go_package name will need to be updated to match this repo, and the actual codegen will need to be ported as well. We will no longer be able to use a direct reference to the .proto files, so we may need to use git submodules or a tool like buf in order to build the needed files.

[kou]

Package name change in apache/arrow: apache/arrow#44035

[kou]

How about referring apache/arrow's format/ via an environment variable?
#114