fix: add missing websocket options to Endpoint validation

[edgurgel]

Valid options from websock_adapter:

https://github.com/phoenixframework/websock_adapter/blob/80901f46c8864cb8bd5231c32b7171b9d0e330ce/lib/websock_adapter.ex#L84-L89

  {:timeout, timeout} -> [idle_timeout: timeout]
  {:compress, _} = opt -> [opt]
  {:max_frame_size, _} = opt -> [opt]
  {:validate_utf8, _} = opt -> [opt]
  {:active_n, _} = opt -> [opt]
  {:deflate_options, deflate_options} -> [deflate_opts: deflate_options]

[josevalim]

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