Decide what to do about the data column of (work)sheet metadata

[jennybc]

>   sheets_sheet_data(ss)
Auto-refreshing stale OAuth token.
# A tibble: 5 x 8
  name     index         id type  visible grid_rows grid_columns data  
  <chr>    <int>      <int> <chr> <lgl>       <int>        <int> <list>
1 Africa       0  780868077 GRID  TRUE         1000           26 <NULL>
2 Americas     1   45759261 GRID  TRUE         1000           26 <NULL>
3 Asia         2 1984823455 GRID  TRUE         1000           26 <NULL>
4 Europe       3 1503562052 GRID  TRUE         1000           26 <NULL>
5 Oceania      4 1796776040 GRID  TRUE         1000           26 <NULL>

See that data column? Should I get rid of it or leave the TODO in place to maybe populate it through some as-yet-undetermined interface? If it stays, perhaps it should be called cells (if it's one-row-per-cell), so as to cause less confusion with data from the function's name, which really refers to metadata.

[StatisMike]

@jennybc If this column is in the future intended to contain data (and properties, like formats!) of individual cells, I would suggest naming it grid_data to reflect the object on the Sheets API side.