[FIX] xlsx: convert #REF at export to xlsx

[hokolomopo]

[FIX] xlsx: convert #REF at export to xlsx:

Reference errors in excel are #REF!, not #REF.

[FIX] parser: inconsistent handling of #REF

Depending on how we get a formula with #REF, the parser can have
different behavior even if the formula is the same.

• If we write directly =#REF (or it comes from a snapshot), the parser
  will throw an error.
• If we write =A1, then delete the row 1 to get =#REF, the parser will
  return a REFERENCE token with an #REF value.

This is a bit of a problem when exporting the data to xlsx: since
we parse the formulas to know whether we need to export it, we get
a different result depending on how we got the #REF.

Task: 4207052

review checklist

• feature is organized in plugin, or UI components
• support of duplicate sheet (deep copy)
• in model/core: ranges are Range object, and can be adapted (adaptRanges)
• in model/UI: ranges are strings (to show the user)
• undo-able commands (uses this.history.update)
• multiuser-able commands (has inverse commands and transformations where needed)
• new/updated/removed commands are documented
• exportable in excel
• translations (_t("qmsdf %s", abc))
• unit tested
• clean commented code
• track breaking changes
• doc is rebuild (npm run doc)
• status is correct in Odoo

[robodoo]