Build a container with LibreOffice for pptx->PDF auto conversion

[sosahi]

Need to:

1. build a container with pre-installed LibreOffice and push to the NGC Staging
2. Scan the container for OSS pkgs
3. Submit a RFR to OSRB team

LibreOffice License
"LibreOffice is licensed under the Mozilla Public License version 2.0 (MPL v2.0), which is a weak copyleft open-source license"

The RFE for pptx->PDF conversion has been raised by DataStax as well