Allow pushing binary data

[the-mikedavis]

Slipstream.push/5 should allow pushing binary data as a binary WebSocket frame. The same is allowed on the server side (docs). The typespec should become:

 @spec push(
         socket :: Socket.t(),
         topic :: String.t(),
         event :: String.t(),
-        params :: json_serializable(),
+        params :: json_serializable() | {:binary, binary()},
         timeout :: timeout()
       ) :: {:ok, push_reference()} | {:error, reason :: term()}

and anything passed in as {:binary, data} should not be passed through the serializer.

See https://github.com/NFIBrokerage/slipstream/issues/28#issuecomment-1477998841