Bug 25242: (QA follow-up) Colwidth on results table

Bug 25242: (QA follow-up) Colwidth on results table

Prior to this patch, the column width on the opac-results table were not
fixed or calculated by a datatable; As such when we introduced the
'table-layout: fixed' property all columns were given equal share of the
table, which resulted in most cases in a three way split between a
checkbox, an empty cell and the actual content.

This patch sets the width for the selectcol to '1ch' for the single
character checkbox and updates the second columns class to 'numcol' as
it is not used for selection but rather result numbering and sets a
fixed width of '4ch' allowing for results upto 3 digits (plus the
period) to display correctly without wrapping.

Test plan
1/ Apply the patches and run the yarn build process to update the .css
2/ Perform a search and varify that the results table looks reasonable
3/ Disable OPACHiddenItems and perform a search again.
4/ Confirm the table looks reasonable still
5/ Signoff

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>