Don't use Zend\Escaper\Escaper directly in the table cell field helpers.

\Zend\Escaper\Escaper does not play nicely with nulls because it expects
UTF-8 strings.  This caused issues when TableCell field helpers used it
because the values being rendered in a table cell are often null.  To
avoid this, these helpers now use \Dewdrop\View\View, which wraps
Escaper and casts all values passed into it as strings.  View has all
the public methods from Escaper, so older code calling the now
deprecated getEscaper() method will still work.