LP#1855931: (follow-up) make grid filter control cells wrap as well

LP#1855931: (follow-up) make grid filter control cells wrap as well

This patch applies "word-wrap: normal" to filter control cells
as well, making it more likely that they will stay aligned with
the width of their corresponding header cells. This can be tested
by adding visible columns to the "Grid with filtering" table in
the Angular sandbox (/eg2/en-US/staff/sandbox) and verifying that
the column after "Circulating Library" continues to have its
filter widget stay aligned with its label.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>