Swarm stops to respond when try to find name

If you try to run `Swarm.whereis_name(name)` while `Swarm.register_name(name, Sup....)` didn't finish yet, the application stops to respond.

```elixir
defmodule MyDynamicSupervisor do
use DynamicSupervisor

# Initialization

def register(name) do
child_spec = %{
id: MyActor,
start: {MyActor, :start_link, [name]},
restart: :transient
}

case DynamicSupervisor.start_child(__MODULE__, child_spec) do
{:error, {:already_started, pid}} -> {:ok, pid}
{:ok, pid} -> {:ok, pid}
end
end
end
```

```elixir
defmodule MyActor do
use GenServer

def start_actor(name) do
{:ok, pid} = Swarm.register_name(name, MyDynamicSupervisor, :register, [name])
end

def start_link(name) do
GenServer.start_link(__MODULE__, name)
end

def init(name) do
pid = Swarm.whereis_name(name) # At this moment, the application stops to respond
{:ok, name}
end
end
```

Start by reproducing the issue with the provided MyDynamicSupervisor and MyActor example, focusing on Swarm.register_name and Swarm.whereis_name during child initialization. Trace the registration and lookup behavior when registration has not completed, then verify that the application remains responsive and that name lookup returns an appropriate result instead of blocking indefinitely.

Written by the indexing model from the issue text.