Rework log streaming and related functions (#1802)

closes #1801
closes #1815 
closes #1144
closes  #983
closes  #557
closes #1827
regression of #1791

# TODO
- [x] adjust log model
- [x] add migration for logs
- [x] send log line via grpc using step-id
- [x] save log-line to db
- [x] stream log-lines to UI
- [x] use less structs for log-data
- [x] make web UI work
  - [x] display logs loaded from db
  - [x] display streaming logs
- [ ] ~~make migration work~~ -> dedicated pull (#1828)

# TESTED
- [x] new logs are stored in database
- [x] log retrieval via cli (of new logs) works
- [x] log streaming works (tested via curl & webui)
- [x] log retrieval via web (of new logs) works

---------

Co-authored-by: 6543 <6543@obermui.de>

server/pipeline/queue.go

@@ -49,9 +49,6 @@ func queuePipeline(repo *model.Repo, pipelineItems []*pipeline.Item) error {
 			Timeout: repo.Timeout,
 		})
 
-		if err := server.Config.Services.Logs.Open(context.Background(), task.ID); err != nil {
-			return err
-		}
 		tasks = append(tasks, task)
 	}
 	return server.Config.Services.Queue.PushAtOnce(context.Background(), tasks)