Move-out messages not being handled in Elixir client

[balegas]

Triggering a move-out with the tagged_subqueries algorithm leads to the client throwing:

01:13:40.592 [error] Shape stream error: %FunctionClauseError{module: Electric.Client.Message, function: :parse, arity: 3, kind: nil, args: nil, clauses: nil}

[balegas]

Assigning this to @icehaunter but we should handover to someone else.