Ffpuppet

- API changes
- Set `soft_rss_limit_mb=5000` to help detect issues and avoid system OOMs
- Set `max_allocation_size_mb=512` to help detect issues and avoid system OOMs
- Add ability to specify global working directory
- Add Pernosco debugger option
- Include 'taskcluster-build-task' in rr trace if available

Bugfix: Call mdsw even if symbols path is missing when a minidump is found