Local platform mode that applies update the the current working directory

[GiuseppeIII]

When running renovate with RENOVATE_PLATFORM=local it would be nice if there would be some way to have whatever changes would normally be made, added to the current working directory (or to a local branch, but that seems to be getting away from platform local and closer to a local mode for a given platform). This would be useful not just for testing, but also when trying to update dependencies locally instead of using each tools own update methods.

I thought

RENOVATE_PLATFORM=local
RENOVATE_DRY_RUN=false

might allow this, but this errors with "message": "Cannot sync git when platform=local",