Add stream protocol version

[benbjohnson]

Currently, if a replica running an older version of LiteFS connects to a newer version of LiteFS which has new stream frame types, it will error out with:

disconnected from primary with error, retrying: next frame: invalid stream frame type: ...

We should begin versioning the stream protocol so we can explicitly check that the accepted version when a node first connects.

We should keep attempting to connect (in case the primary changes to a different version), however, the error message could be improved. We could also increase the retry the delay so we aren't spamming logs so much.