fix test server setup: (#549)

* fix test server setup:
- go map access is not deterministic
- this can lead to a route: /foo/bar/1 matching /foo/bar before matching /foo/bar/1 if the map iteration go through /foo/bar first since the regex match wasn't bound to start and end anchors
- registering handlers now converts * in routes to .* for proper regex matching
- test server route handling now tries to fully match the handler route

* add missing /v1 prefix to fine-tuning job cancel test server handler

fine_tuning_job_test.go

@@ -42,7 +42,7 @@ func TestFineTuningJob(t *testing.T) {
 	)
 
 	server.RegisterHandler(
-		"/fine_tuning/jobs/"+testFineTuninigJobID+"/cancel",
+		"/v1/fine_tuning/jobs/"+testFineTuninigJobID+"/cancel",
 		func(w http.ResponseWriter, _ *http.Request) {
 			resBytes, _ := json.Marshal(openai.FineTuningJob{})
 			fmt.Fprintln(w, string(resBytes))