"View full contents" for text cells should be available from context menu

[rbasralian]

When a String column is too narrow to display its full contents, there is a button that lets you open a dialog that shows the full contents:

This is helpful because the "Cell Contents" dialog lets you select and copy just a portion of the text:

However, if the column happens to already be wide enough to display the full cell contents, there is no way to get to the "Cell Contents" dialog, since the button disappears:

And it is not available in the context menu:

[vbabich]

Label as "View Cell Contents". Place as own menu group at the end of list. Only show on string columns.