made a checkbox to Trim extra white spaces from both ends
while using seperators in 'Text Imort'

Change-Id: Ib05d9b17525e3ebec380ec8b7eebfa35fff78f01
Reviewed-on: https://gerrit.libreoffice.org/46177Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Manuj Vashist <manujvashist@gmail.com>
Reviewed-by: Heiko Tietze <tietze.heiko@gmail.com>
Tested-by: Heiko Tietze <tietze.heiko@gmail.com>