Feature Request: Add Concurrency Handling to sheet_append()

[matmu]

I have observed that the sheet_append() function does not handle concurrent writes correctly, which can result in issues where concurrent writes overwrite each other's rows. The Google Sheets API v4 already offers method spreadsheets.values.append (ref) with parameter insertDataOption="INSERT_ROWS" to manage concurrent writes effectively (also see here). Since this functionality does not appear to be available in the googlesheets4 package, I would like to formally request the addition of this feature.