[CHORE]: fj-doc-mod-fop support keep-togetjer

[fugerit79]

Module

fj-doc-mod-fop - PDF, XSL-FO doc handler based on Apache FOP

Expected Behavior

Support for xsl fo keep-together attribute

Other information

I want to add support for the keep-together attribute.

Edit : In the end we added a property mod-fop-xslt-path to add custom xsl transformation