createSheet adds a tab to an existing spreadsheet.
Example
Inputs
spreadsheet and unique title are required. Optional positive rowCount and
columnCount, nonnegative frozenRowCount and frozenColumnCount, zero-based
index, hidden, and rightToLeft set the initial sheet. account selects
the Google account.
Output
ReturnsSheet metadata with sheetId, title, zero-based index, grid counts,
frozen counts, visibility, direction, type, and an empty tables array.