Bulk Operations should have a --debug mode which maintains logs and tempfiles

[prescod]

Please describe the nature of this feature request

• I'm interested in functionality that solves a current problem or limitation in how CumulusCI works.

Does your feature request solve a current problem? Please describe.

Data loading is complex and often requires debugging. CCI's tools for doing so could be enhanced.

Describe the solution you'd like The --debug option should imply that tempfiles are kept around and their names should be printed on logs.

Additional context This was requested by an internal team but I need it frequently myself.

Relates to #2481