Migrate Flight and FlightSql Proto Gen

[Flight](https://github.com/apache/arrow/blob/main/format/Flight.proto) and [FlightSql](https://github.com/apache/arrow/blob/main/format/FlightSql.proto) definitions are still in apache/arrow.

The [go_package](https://github.com/apache/arrow/blob/main/format/Flight.proto#L23) 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](https://buf.build) in order to build the needed files.

Start with format/Flight.proto and format/FlightSql.proto, especially the go_package declaration in Flight.proto. Trace the existing code-generation setup in arrow-go, then evaluate whether git submodules or buf can provide the definitions. Done means the Flight and FlightSql generated code is ported and builds without direct references to apache/arrow proto files.

Written by the indexing model from the issue text.