neon_local endpoint create: require the version OR query pageserver or storage controller for it

[koivunej]

It does not make sense endpoint creation defaults to pg15 regardless of the version the tenant (not timeline, it's per tenant) is using. I am calling it per tenant since we only have one version of walredo running right now.

I think we could easily do either in $subject; defaulting is just a timesink where one learns of the option through first creating a wrong version by inspecting the compute.log for start failure reason, cleans up the old version, re-creates a new one.

There are other sharp edges with neon_local and endpoints.