Subscript and superscript parsers should produce round-tripping `Syntax`

MWE:

import Mathlib.Util.Superscript

local syntax:arg term:max noWs superscript(term) : term
local macro_rules | `($a:term$b:superscript) => `($a ^ $b)

set_option pp.raw true
set_option pp.raw.showInfo true
set_option trace.Elab.command true

#guard 2⁽¹⁺¹⁾ = 4

-- Current output:
/-
[Elab.command] ✅️ (Command.guardCmd
     "#guard"
     («term_=_»
      (_private._stdin.0.term___
       (num "":339:"2":340:"")
       (Mathlib.Tactic.superscript
        (Term.paren
         (Term.hygienicLParen "":340:"(":343:"" (hygieneInfo "":343:`[anonymous]:343:""))
         («term_+_» (num "":343:"1":345:"") "":345:"+":348:"" (num "":348:"1":350:""))
         "":350:")":353:" ")))
      "":354:"=":355:" "
      (num "4")))
-/

-- Possible correct output:
/-
[Elab.command] ✅️ (Command.guardCmd
     "#guard"
     («term_=_»
      (_private._stdin.0.term___
       (num "":339:"2":340:"")
       (Mathlib.Tactic.superscript
        (Mathlib.Tactic.superscript.body
         (Term.paren
          (Term.hygienicLParen "":340:"⁽":343:"" (hygieneInfo "":343:`[anonymous]:343:""))
          («term_+_» (num "":343:"¹":345:"") "":345:"⁺":348:"" (num "":348:"¹":350:""))
          "":350:"⁾":353:" "))))
      "":354:"=":355:" "
      (num "4")))
-/

Possible workaround: Make the parser retain the original source tokens and define a macro that converts the body of the sub- or superscript to the form that is accepted by the elaborator.

Discovered while auto-formatting all of Mathlib.

Start with Mathlib.Util.Superscript and reproduce the provided MWE, including the raw Syntax output and auto-formatting context. Investigate how the subscript and superscript parsers represent their source tokens. Done means the resulting Syntax preserves the original delimiters and body tokens and matches the proposed round-tripping output.