PAGE_DBWIZARD_MYSQL_INTRO and PAGE_DBWIZARD_SPREADSHEET conversion to .ui

Change-Id: I5d14fc4bd051c37802c0689d55d8557e26312a5d
Reviewed-on: https://gerrit.libreoffice.org/10606
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>