LBANN: add support for new python front end (#11395)

* LBANN: add python dependency and required python library dependencies
* LBANN: add version 0.99 as alias for develop branch
* LBANN: build Conduit library by default
* LBANN: CUB is included with Hydrogen for later versions
* New package: py-graphviz (dependency for LBANN)
* New package: py-texttable (dependency for LBANN)
* New package: py-onnx (dependency for LBANN)
* New package: py-typing-extensions (dependency for py-onnx)
* Conduit: add version 0.4.0
* NCCL: Add versions 2.4.6-1 and 2.4.2-1
* Protobuf: Add versions 3.7.1 and 3.7.0
* py-protobuf: add version 3.7.1
* py-typing: add version 3.6.4
* cuDNN: add versions. The source differs depending on the
  architecture, so the versions include a suffix to encode this.
  For example this adds 7.5.1-10.1-x86_64 as well as
  7.5.1-10.1-ppc64le
* cuDNN: Newer versions require newer versions of CUDA
* Hydrogen: add configure options for CUB and Aluminum