Support re-using an environment for local developer experience

[mfisher87]

As I'm developing a recipe, I'm finding myself a bit frustrated by the venvception process which builds a fresh environment every time, lengthening my feedback loop. I'd like to be able to re-use an environment I created in a previous build if I know for sure it hasn't changed, for example with a CLI flag.

Reading the venvception code, this isn't something the library supports out of the box.

[norlandrhagen]

I regularly find myself in the same situation @mfisher87! Recreating an environment every run makes debugging really difficult.