Rework the Compress Image dialog

* Switch to an horizontal layout
* Drop the expander and make file info always visible at the right side
* Resizing didn’t make sense when the expander was there, still doesn’t
* Sentence capitalization for radio buttons and check boxes, see HIG
* Add it a title!
* Make it modal

Change-Id: I08215b122bd9466c33fdc93e3c007f4aaf47b4e5
Reviewed-on: https://gerrit.libreoffice.org/11671
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>