Add Support for Threshold Conditions by Environment

As a Contrast user, I want to break the beginning of my pipeline based on vulnerabilities in a lower environment so that I can enable/allow exploratory testing to occur as an out-of-band process.

Long-running (or multiple-run) process in a lower environment such as development may generate vulnerabilities that should not be promoted to higher level environments. Having the first step of a build (almost pre-build step) of a deployment pipeline check *_the last_* environments results would be beneficial.

This would also allow for increasing policy scrutiny as code progress through higher level environments.

No source files, tests, or entry points are named. Start by locating the plugin's pipeline-condition implementation and its handling of vulnerability results across environments; done means a pipeline can gate its first step using the last lower-environment result while preserving stricter checks in higher environments.

Written by the indexing model from the issue text.