fix: keep a step's own with: values out of its inputs context (#1192)

A step's `if:`, its `continue-on-error:` and its `run:` script resolved `inputs.*` from the step's own `INPUT_*` env. A `with:` key colliding with a workflow input flipped conditions, and any `INPUT_`-shaped variable from `env:` or a `GITHUB_ENV` write forged an input that never existed.

GitHub evaluates all three in the enclosing scope: the workflow inputs, or for a composite action's steps that action's inputs. Action-input interpolation is the one place that legitimately sees a step's own `with:`, so it keeps its own evaluator.

Fixes https://gitea.com/gitea/runner/issues/1191, ports https://github.com/nektos/act/pull/2473 and extends it to the pre and post stages.

---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1192
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: ABiscuitttt <773542570@qq.com>

act/runner/action.go

@@ -346,7 +346,7 @@ func execAsDocker(ctx context.Context, step actionStep, actionName, actionDir, b
 			logger.Debugf("image '%s' for architecture '%s' already exists", image, rc.Config.ContainerArchitecture)
 		}
 	}
-	eval := rc.NewStepExpressionEvaluator(ctx, step)
+	eval := rc.NewActionInputsExpressionEvaluator(ctx, step)
 	cmd, err := shellquote.Split(eval.Interpolate(ctx, step.getStepModel().With["args"]))
 	if err != nil {
 		return err
@@ -410,13 +410,13 @@ func evalDockerArgs(ctx context.Context, step step, action *model.Action, cmd *[
 	}
 	mergeIntoMap(step, step.getEnv(), inputs)
 
-	stepEE := rc.NewStepExpressionEvaluator(ctx, step)
+	stepEE := rc.NewActionInputsExpressionEvaluator(ctx, step)
 	for i, v := range *cmd {
 		(*cmd)[i] = stepEE.Interpolate(ctx, v)
 	}
 	mergeIntoMap(step, step.getEnv(), action.Runs.Env)
 
-	ee := rc.NewStepExpressionEvaluator(ctx, step)
+	ee := rc.NewActionInputsExpressionEvaluator(ctx, step)
 	for k, v := range *step.getEnv() {
 		(*step.getEnv())[k] = ee.Interpolate(ctx, v)
 	}