previewer: d3js csv previewer huge table ui block

* Fixes ui blocking by rendering table incrementally.

Signed-off-by: Adrian Pawel Baran <adrian.pawel.baran@cern.ch>
can you try something like `{{ _("This preview contains first %{x_number} rows.", x_number="<i id="rows_number">%d</i> "|format(rows)) }}`?