Attribute attachment not preserved in refmt.

Repro: 4.02.3 on master branch:

echo '[@attr] x + [@attr2] y;' | refmt

    [@attr]
    x + [@attr2] y;

echo '([@attr] x) + [@attr2] y;' | refmt

      [@attr] x + [@attr2] y;

Notice that the parens were dropped. And they are in fact distinct ASTs, and that distinction is not preserved at print time:

echo '[@attr] x + [@attr2] y;' | refmt --print ast
[
  structure_item ([1,0+0]..[1,0+22])
    Pstr_eval
      attribute "attr"
        []
    expression ([1,0+8]..[1,0+22])
      Pexp_apply
      expression ([1,0+10]..[1,0+11])
        Pexp_ident "+" ([1,0+10]..[1,0+11])
      [
        <label> ""
          expression ([1,0+8]..[1,0+9])
            Pexp_ident "x" ([1,0+8]..[1,0+9])
        <label> ""
          expression ([1,0+12]..[1,0+22])
            attribute "attr2"
              []
            Pexp_ident "y" ([1,0+21]..[1,0+22])
      ]
]
jwalkes-MacBook:reason jwalke$ echo '([@attr] x) + [@attr2] y;' | refmt --print ast
[
  structure_item ([1,0+0]..[1,0+24])
    Pstr_eval
    expression ([1,0+0]..[1,0+24])
      Pexp_apply
      expression ([1,0+12]..[1,0+13])
        Pexp_ident "+" ([1,0+12]..[1,0+13])
      [
        <label> ""
          expression ([1,0+0]..[1,0+11])
            attribute "attr"
              []
            Pexp_ident "x" ([1,0+9]..[1,0+10])
        <label> ""
          expression ([1,0+14]..[1,0+24])
            attribute "attr2"
              []
            Pexp_ident "y" ([1,0+23]..[1,0+24])
      ]
]

Start by reproducing the two examples with refmt and compare their formatted output with the --print ast output shown in the issue. Trace the refmt formatting path for attributed expressions and parentheses; done means formatting preserves the distinction between the two ASTs without dropping required parentheses.