feat: gate set-env/add-path and render annotation locations (#1109)

`::set-env::` and `::add-path::` let a step rewrite the environment of every later step from its own output, which the runner honoured silently. They are now refused, as GitHub has done since 2020, and `ACTIONS_ALLOW_UNSECURE_COMMANDS` opts back in per step or job. Support for that variable is new here too, and is the only opt-in, matching GitHub rather than adding a runner config key on top.

Annotations keep their source location: Gitea has no annotation store and its web UI strips command properties, so `::error file=main.go,line=12::msg` is rendered as `::error::main.go:12: msg`.

`DEVELOPMENT.md` writes down the log line encoding rules this relies on.

---------

Co-authored-by: silverwind <me@silverwind.io>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1109
Reviewed-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-authored-by: bircni <bircni@icloud.com>

act/runner/job_executor.go

@@ -66,7 +66,7 @@ func reportStepError(ctx context.Context, rc *RunContext, err error) {
 		rc.markInterrupted(ctx.Err())
 		return
 	}
-	common.Logger(ctx).Errorf("##[error]%s", escapeCommandData(err.Error()))
+	common.Logger(ctx).Errorf("##[error]%s", EscapeCommandData(err.Error()))
 	common.SetJobError(ctx, err)
 	rc.markFailed()
 }
@@ -260,7 +260,7 @@ func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executo
 
 			logger.Infof("Cleaning up container for job %s", rc.JobName)
 			if err = info.stopContainer()(ctx); err != nil {
-				logger.Errorf("Error while stop job container: %v", err)
+				logger.Errorf("##[error]%s", EscapeCommandData("Error while stop job container: "+err.Error()))
 			}
 
 			// For Gitea