Add needs job output (#629)

* Add outputs field to job model

* Add output interpolation for jobs

* Add otto config reference for interpolated job output values into 'needs' context

* Add output interpolation call after job has completed.

* gofmt

* Remove whitespace

* goimports

Co-authored-by: Casey Lee <cplee@nektos.com>

pkg/runner/run_context.go

@@ -262,7 +262,7 @@ func (rc *RunContext) newStepExecutor(step *model.Step) common.Executor {
 		rc.ExprEval = exprEval
 
 		common.Logger(ctx).Infof("\u2B50  Run %s", sc.Step)
-		err = sc.Executor()(ctx)
+		err = sc.Executor().Then(sc.interpolateOutputs())(ctx)
 		if err == nil {
 			common.Logger(ctx).Infof("  \u2705  Success - %s", sc.Step)
 		} else {