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 <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1192
Reviewed-by: silverwind <[email protected]>
Co-authored-by: ABiscuitttt <[email protected]>

act/runner/step_action_remote.go

@@ -245,7 +245,7 @@ func (sar *stepActionRemote) getCompositeRunContext(ctx context.Context) *RunCon
 		// input for this action during the main stage, but the env
 		// was already created during the pre stage)
 		env := evaluateCompositeInputAndEnv(ctx, sar.RunContext, sar)
-		sar.compositeRunContext.Env = env
+		sar.compositeRunContext.setActionEnv(env)
 		sar.compositeRunContext.ExtraPath = sar.RunContext.ExtraPath
 	}
 	return sar.compositeRunContext