## Problem
As part of https://github.com/neondatabase/neon/issues/8614 we need to
pass options to START_WAL_PUSH.
## Summary of changes
Add two options. `allow_timeline_creation`, default true, disables
implicit timeline creation in the connection from compute. Eventually
such creation will be forbidden completely, but as we migrate to
configurations we need to support both: current mode and configurations
enabled where creation by compute is disabled.
`proto_version` specifies compute <-> sk protocol version. We have it
currently in the first greeting package also, but I plan to change tag
size from u64 to u8, which would make it hard to use. Command is more
appropriate place for it anyway.
6fe4c6798f