save_file's note for a key in `options` that the written format doesn't
read named every .ai file a PDF-compatible .ai, also when the save wrote
a version 7 file (`aiVersion: "7"`) or one without PDF content
(`pdfCompatible: false`).
The save itself now writes that note, beside its note on a top-level
`compress`, `version`, `preview` or `precision`, and names the file it
writes, including when it reuses the options the document was last saved
with. save_file returns the save's reply unchanged, and
`run_command document.save` and the other save commands give the same
notes.