Investigate mapping enter and esc to enter and exit full view of cell data in Data Viewer

[joyceerhl]

The original plan for #298 was to display the untruncated version of cells only when the user hits enter while a cell is active and selected, and to exit that view when the user hits escape. This is currently blocked because setting 'autoEdit: false' in the SlickGrid settings results in focus getting lost after exiting edit mode on one cell, which would constitute a regression and an accessibility bug. This work item is for investigating how to map those keys to enter/esc without losing the existing tabbing behavior.