Returns binary containing spec representation of given udt name
t() :: %EctoGen.Database.DbRoutineParameter{ mode: term(), name: term(), parameter_default: term(), position: term(), udt_name: term() }
iex> udt_name_to_elixir_term("text") "binary()" iex> udt_name_to_elixir_term("int") "integer()" iex> udt_name_to_elixir_term("timestamp") "DateTime.t()" iex> udt_name_to_elixir_term("timestamptz") "DateTime.t()"