fdo#65430 add OnItemDblClicked and setOpenTemplateHdl in templateSearchView

Currently only templateAbstractView had such handler, which are
templateLocalView and templateRemoteView are based on.

Change-Id: I6694d0804a8b7e58abc0ddc970e811d053394d6f
Reviewed-on: https://gerrit.libreoffice.org/7918
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>