Keyboard shortcuts for spreadsheet

[andrewtpham]

We would like to add keyboard shortcuts for the following use cases:

• When a user has selected a cell, they can click tab in order to go to the cell to its right (next column).

• When a user is currently editing a cell, they can click tab in order to go to the cell to its right (next column).
  

• When a user has selected a cell, they can click enter in order to edit the cell.
  

• When a user is currently editing a cell, they can click esc in order to exit editing the cell and go back to only the cell only being selected.