Default folder support

**Is your feature request related to a problem? Please describe.**
- Add in the ability to specify a default folder.
- determine where default folder configuration should be saved to
- copy in default folder to plugins env folder during run
- add to exported env

No file, test, or entry point is named in the issue. Start by tracing how configuration is stored, how the plugins environment is assembled during a run, and how the exported environment is produced; done means a specified default folder is persisted, copied into the plugins environment, and included in the export.

Written by the indexing model from the issue text.