Prefer autoscaling based on jobs rather than workflows if available (#114)

Adds the ability to autoscale on jobs in addition to workflows. We fall back to using workflow metrics if job details are not present.

Resolves #89

github/fake/options.go

@@ -2,6 +2,7 @@ package fake
 
 type FixedResponses struct {
 	ListRepositoryWorkflowRuns *Handler
+	ListWorkflowJobs           *MapHandler
 }
 
 type Option func(*ServerConfig)
@@ -15,6 +16,15 @@ func WithListRepositoryWorkflowRunsResponse(status int, body string) Option {
 	}
 }
 
+func WithListWorkflowJobsResponse(status int, bodies map[int]string) Option {
+	return func(c *ServerConfig) {
+		c.FixedResponses.ListWorkflowJobs = &MapHandler{
+			Status: status,
+			Bodies: bodies,
+		}
+	}
+}
+
 func WithFixedResponses(responses *FixedResponses) Option {
 	return func(c *ServerConfig) {
 		c.FixedResponses = responses