Implement actions badge svgs (#28102)

replace #27187 
close #23688
The badge has two parts: label(workflow name) and message(action
status). 5 colors are provided with 7 statuses.
Color mapping:
```go
var statusColorMap = map[actions_model.Status]string{
	actions_model.StatusSuccess:   "#4c1",    // Green
	actions_model.StatusSkipped:   "#dfb317", // Yellow
	actions_model.StatusUnknown:   "#97ca00", // Light Green
	actions_model.StatusFailure:   "#e05d44", // Red
	actions_model.StatusCancelled: "#fe7d37", // Orange
	actions_model.StatusWaiting:   "#dfb317", // Yellow
	actions_model.StatusRunning:   "#dfb317", // Yellow
	actions_model.StatusBlocked:   "#dfb317", // Yellow
}
```
preview:

![1](5465cbaf-23cd-4437-9848-2738c3cb8985)

![2](ec393d26-c6e6-4d38-b72c-51f2494c5e71)

![3](3edb4fdf-1b08-4a02-ab2a-6bdd7f532fb2)

![4](8c189de2-2169-4251-b115-0e39a52f3df8)

![5](3fe22c73-c2d7-4fec-9ea4-c501a1e4e3bd)

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: delvh <dev.lh@web.de>

routers/web/web.go

@@ -1371,6 +1371,9 @@ func registerRoutes(m *web.Route) {
 				m.Delete("/artifacts/{artifact_name}", actions.ArtifactsDeleteView)
 				m.Post("/rerun", reqRepoActionsWriter, actions.Rerun)
 			})
+			m.Group("/workflows/{workflow_name}", func() {
+				m.Get("/badge.svg", actions.GetWorkflowBadge)
+			})
 		}, reqRepoActionsReader, actions.MustEnableActions)
 
 		m.Group("/wiki", func() {