feat: 基本HTTP服务器

- REST API: health用于检测服务器REST API正常运行

interval/api/handler/health.go

@@ -0,0 +1,8 @@
+package handler
+
+import "net/http"
+
+func Health(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte("OK"))
+}