[Bug] azure-pipeline-variables is poorly named

The `azure-pipeline-variables` feature added by #11 is poorly named. This passes the "variables" as "parameters" to the ADO pipeline. This makes it very confusing about what's actually happening with the values.

Here's the code in question that demonstrates why this is confusing: https://github.com/Azure/pipelines/blob/f1fe65f3daf2f705ca49c37ef172109e3e7c0d8f/src/pipeline.runner.ts#L95

Start with src/pipeline.runner.ts at the linked line and review the feature introduced by issue #11. Trace how azure-pipeline-variables is exposed and passed to the Azure DevOps pipeline, then identify all references that would need a clearer name. Done means the naming accurately describes the values being passed and remains consistent across the feature.

Written by the indexing model from the issue text.