Simplify and reenable backtraces

Add tests to verify support for backtraces is available.

Example: https://github.com/Kitware/kwiver
Old (3.10) codemodel json : 14 MBs
New codemodel json with traces : 4MB
New codemodel json without traces : 2MB
Status Name Job ID Coverage
  External
passed ghostflow-branch-check-master

passed ghostflow-commit-check