support for cpp

[matdibu]

hello! I got this error while running cdxgen

Failed to run atom-tools. Use the atom container image or perform 'pip install atom-tools' and re-run this command. Exception: 
Unknown origin type: cpp

so I tried to run it manually to confirm the behavior

$ atom-tools convert -t cpp

Unknown origin type: cpp

looks like cpp isn't supported, right?

atom-tools/atom_tools/cli/commands/convert.py

Line 88 in d1461e6

supported_types = {'java', 'jar', 'python', 'py', 'javascript', 'js', 'typescript', 'ts', "ruby", "rb", "scala", "sbt"}